British and French military aircraft are preparing to protect the Libyan rebel stronghold of Benghazi after the UN security council voted in favour of a no-fly zone and air strikes against Muammar Gaddafi's forces.
With Gaddafi's troops closing in on Benghazi, the French prime minister, François Fillon, said "time is of the essence" and that France would support military action within hours of the vote. But US sources were more cautious, speaking of action in days rather than hours.
Fighter jets and bombers could take off from French bases along the Mediterranean coast, about 750 miles from Libya. Several Arab countries have promised to join the operation. Washington supported the resolution, a complete turnaround after weeks of resisting no-fly zone proposals, but has not yet said what role, if any, it would play in military action.
The 15-member security council voted in favour of a resolution authorising all necessary measures, other than occupation, to protect civilians under threat of attack, including Benghazi. Ten members voted in favour, with five, including China, Russia and Germany, abstaining. The resolution ruled out putting troops on the ground.
Al-Jazeera TV showed rebels in Benghazi last night celebrating after the no-fly vote was announced. Gaddafi called the vote a "flagrant colonisation" and warned of dire consequences.
He also threatened that no mercy would be shown to residents of Benghazi who resisted him, and that he was ordering an attack on Benghazi beginning last night.
Earlier, his regime issued a strong warning that it would target all maritime traffic in the Mediterranean if it was targeted by foreign forces.
In a statement broadcast on Libyan television, the defence ministry said: "Any foreign military act against Libya will expose all air and maritime traffic in the Mediterranean Sea to danger and civilian and military [facilities] will become targets of Libya's counterattack."
Residents and a rebel spokesman reported three air strikes on the outskirts of the city on Thursday, including at the airport, and another air raid further south. There was also heavy fighting in residential areas of nearby Ajdabiya, where around 30 people were killed, the TV station al-Arabiya reported.
The UN resolution was co-sponsored by Britain, France, Lebanon and the US.
A security council source said the resolution would impose a no-fly zone over Libya but that was no longer enough. "The resolution authorises air strikes against tank columns advancing on Benghazi or engaging naval ships bombarding Benghazi," he said. Nato would have to meet before committing any forces.
The US secretary of state, Hillary Clinton, who is visiting Tunisia, said a no-fly zone would "require certain actions taken to protect the planes and the pilots, including bombing targets like the Libyan defence systems." David Cameron spoke to leaders of Arab countries on Wednesday night and yesterday to persuade them to take part. The US had demanded Arab involvement to ensure that the west could not be accused of imposing its will on the Arab world. The prime minister also spoke to African and European leaders as he lobbied for support for the resolution.
Speaking outside the UN security council in New York, Alain Juppé, the French foreign minister, said there was "reason to anticipate that some Arab countries will participate". But he said a land invasion was out of the question. "For us and in the resolution itself there is no question of having people on the ground in Libya."
Germany, which opposes a no-fly zone, remained sceptical about the value of military action. In an interview with the Guardian, Germany's foreign minister, Guido Westerwelle, said Berlin strongly opposed any military intervention in Libya or the use of air strikes against Gaddafi.
Westerwelle warned that the consequences of western military intervention were 'unpredictable' and could affect freedom movements in the Arab world. "Your own instinct is to say 'We have to do something'. But military intervention is to take part in a civil war that could go on for a long time. Germany has a strong friendship with our European partners, but we won't take part in any military operation and I will not send German troops to Libya," he said.
Instead, Westerwelle said there were non-force options that could still be used against Libya, including 'targeted sanctions, political pressure and international isolation."
"Considering alternatives to military engagement is not the same as doing nothing,' he said. He declined to say how Germany would vote ahead of this evening's vote in the UN security council.
William Hague, the foreign secretary, said the resolution was necessary "to avoid greater bloodshed and to try to stop what is happening in terms of attacks on civilians". The British and EU criteria for a no-fly zone – a demonstrable need, a clear legal basis and broad regional support – had all been met, he added.
"This places a responsibility on members of the United Nations and that is a responsibility to which the United Kingdom will now respond," Hague said in remarks at the Foreign Office shortly before heading for talks in Downing Street with Cameron around 11pm last night.
The air operation will be led by the US, Britain and France with help from other countries, including members of the Arab League. French planes will operate from bases on its Mediterranean coast. British planes are expected to fly from the sovereign base at Akrotiri in Cyprus.
"It will be a coalition of countries that have come together," one British government source said. Cameron and Barack Obama discussed the operation in a phone call. Ministers were holding talks late into the night in Downing Street to discuss the next steps.
The prime minister has ripped up his diary today to hold an emergency cabinet on Libya in the morning. He will then make a statement to MPs who are meant just to be discussing backbench private members' bills in the Commons.
Sir Malcolm Rifkind, the former foreign secretary, told the BBC: "I'm absolutely delighted. Without action of this kind, Benghazi would have been a bloodbath. By the standards of the last 20 years, this is a remarkable vote. This is a tremendous morale booster for Libyans."
Washington backed the resolution after the Arab League joined the calls for a no-fly zone. The Obama administration was stalled by a split between Clinton, who favoured the no-fly zone, and the defence secretary, Robert Gates.
Gates, although opposed to the no-fly zone, redeployed US naval vessels close to the Libyan coast and told the president that the military was capable of fighting on a third front. Speculation as to which countries would participate included Saudi Arabia, the United Arab Emirates and Qatar.