A 'winter of discontent' looks imminent as Unison, the country's biggest public sector workers' union, gave formal notice today that its 1.1 million members will be balloted for industrial action in the bitter row over pensions.

A crowd of protesters made their feelings clear in London as marches take place across the country, sparked by a proposed increase in the retirement age for public sector workers and paying more into their pensions The Government face the threat of the biggest outbreak of industrial action since the 1926 General Strike after unions served notice of ballots over the row which will see workers pay an extra 3.2 per cent in pension contributions.

Unison's general secretary, Dave Prentis, said 9,000 separate employer groups would be involved in the action, describing the ballot as 'unprecedented' in scale.

He blamed the Government for the ballot decision, which could see workers in school, hospitals, police and voluntary sectors, join the move.

He said: 'A ballot unprecedented in scale will cover over a million workers in health, local government, schools, further education, police, the voluntary sector and the environment and private sector.

'It's a decision we don't take lightly and the stakes are high, higher than ever before, but now is the time to make our stand.

'It will be hard, we'll be vilified, attacked, set against each other, but we must stay strong and united.'

The union was joined by Unite and the Fire Brigades Union, who all gave notice of ballots in the worsening row over pensions and launched angry attacks against the Government.

Mr Prentis announced to the TUC Congress in London that unions were involved in the 'fight of our lives' over the Government's controversial reforms of pensions, which will see workers pay an extra 3.2 per cent in contributions.

He said Unison would work with the GMB and Unite, which could mean the country grinding to a halt if millions of the members decide to strike together.

His announcement was met with a standing ovation as delegates applauded the move, which brings the prospect of a winter of strikes closer.

Mr Prentis accused the Government of an 'unprecedented' attack on workers with its 'audacious and devious' pension reforms.

Mr Prentis said that exhaustive talks had not worked for the unions: 'We've been patient, we've co-operated, but there comes a time when we say enough is enough because, if we don't, they'll be back for more.

Gail Cartmail, assistant general secretary of Unite, told the conference: 'When the coalition came to power we knew we faced the fight of our lives, we knew they would seek to weaken and divide us.

'While we will never walk away from talks, neither can we sit on our hands. We will support days of action and tactical selective action.'

The Fire Brigades Union's ballot of its 43,000 members raises the threat of a walkout without 'Green Goddess' military cover.

Firefighters last took national strike action in 2003, when Green Goddesses were used as emergency cover, but the ageing military vehicles have since been taken out of service.

Mark Serwotka, general secretary of the Public and Commercial Services union, which has already announced fresh industrial action in November, said today's moves showed that opposition was growing to the Government's 'raid' on public sector pensions.

'Following the hugely successful strike by civil servants, teachers and lecturers in June, there is a clear momentum behind our campaign that ministers cannot ignore, and they must now enter into serious and open negotiations.

'We will now join our colleagues from across the public sector to discuss the nuts and bolts of this fightback, which we fully expect will mean industrial action on a scale not seen for many years.'

Steve Gillan, general secretary of the Prison Officers Association, which is not allowed to take industrial action, warned that his members would defy the law if no deal was reached on pensions.

Brian Strutton, national officer of the GMB, announced that his union's 250,000 public sector members will also be balloted for strikes, warning that industrial action could last for months.

'We are not talking about a day - we are talking about something that is long and hard and dirty, running through the winter, into next year and following the legislative programme right into the summer.'

The dispute will involve hospital and ambulance workers, meals-on-wheels staff, refuse collectors and cemetery workers, he said.

Mr Strutton said recent talks over pension reform had been held between Government ministers and local authority leaders, with unions 'not even in the room'.

Public sector unions will meet later today to discuss co-ordinated action ahead of more talks with the Government planned for next week.

Joining them, workers at four British Sugar plants are to be balloted on industrial action in a dispute over pay and the 'soaring cost of living'.

Unite said 250 members based in the East of England will vote in the coming weeks on whether to launch a campaign of strikes after rejecting a 3.5 per cent pay offer.

The union said it was seeking a pay deal equal to RPI inflation, currently running at 5.2 per cent, plus 0.5 per cent for the year to next April.

Regional officer Mick Doherty said: 'Our members are being hit very hard by the soaring cost of living.

'British Sugar is a very profitable company and despite its complaints that the sugar beet crop was hit by last winter's bad weather, it is well able to afford a decent pay rise.'

The Government hit back at the 'disappointing' strikes, saying they had tried to reach a negotiation with unions.

Prime Minister David Cameron's official spokesman described the calls for strike ballots as 'disappointing', and slammed the industrial action would be irresponsible at a time of economic difficulty.

'Our view is that the best way forward is to continue with talks and we have always been very clear that we should try to have a constructive dialogue with the unions,' said the spokesman.

'Clearly, it is disappointing that there have been calls for industrial action, particularly as the talks are still ongoing.

'On pensions, we have been very clear about the need for reform, but we have also been making the point that even after these reforms come through, public sector pensions will still be amongst the very best available.'

Deputy Prime Minister Nick Clegg, answering questions after a speech in London, said: 'It is very regrettable that they are rushing to announce days of strikes when the discussions are still ongoing.

'It would lovely to wave a magic wand and say we have discovered pots of gold, and the ageing population is not ageing, and, hallelujah, pension funds are entirely sustainable.

'We entered into these discussions in good faith and we will continue to do so."

Cabinet Office Minister Francis Maude, who is leading negotiations for the Government, told BBC News: 'I think the public will be really fed up if they see industrial action damaging the economy, damaging their ability to get to work and earn their own living when (they) may be paying more towards public sector pensions than they are towards their own.

'We want this to be a proper settlement so that we know that public sector workers are going to be able to enjoy these good pensions - better pension schemes than are available almost anywhere else - but that's on a sustainable basis.

'I don't want governments to be coming back in five or 10 years' time and saying 'We need to have another go at this because it wasn't sorted out properly in 2011'.

'I think the unions need to think about the effect on the public and the effect on the economy and on their own members.

'Their own members want to be going to work, they don't want to be giving up a day's pay, or more than that, at a time when we are all of us working under major constraints.'

Increasingly militant transport union leaders joined in with the walkout threats, warning they were planning the ‘biggest campaign’ of civil disobedience in Britain’s history.

They plan to disrupt public services and block motorways as well as declaring they are ready to ‘go to prison’ in protest at proposed changes to pensions.

In a bid to persuade them to stop striking and wrecking the Games, transport bosses have offered hefty bonuses to railway workers amid fears the militant RMT union could wreck the Games with strikes.

Train drivers will pocket up to £1,800 simply for turning up for work during the London Olympics next summer.

Last night, MPs condemned the payments as a ‘bribe’ and accused the unions of holding the public to ransom.

Astonishingly, the Daily Mail understands that the £1,800 bonus deal with Tube drivers does not even include a no-strike clause.

The glaring omission leaves them free to pocket the cash and still cause mass disruption with industrial action.

A senior source connected with the talks said: ‘The drivers could have demanded fur coats for the wives or football season tickets for the men if they wanted.

‘It’s an amazing deal but one which the Tube had to do. There was no alternative.’

Union sources revealed a battle plan has been devised, mapping out ‘blocks’ of strikes running in ‘target areas’ for two to three days at a time.

One union leader said to expect scenes reminiscent of the 1978 ‘winter of discontent’ when rubbish filled the streets.

Another, unnamed, told the BBC: ‘In some areas there will be two or three days. In other areas it will be continuous. In other areas it will be a rolling programme.’