The redeployment of British forces in Iraq to support a US assault on Falluja marks another stage in a creeping return to the colonial era, when popular revolts against occupation were routinely suppressed by overwhelming force. These past episodes, revealed in declassified British government files, provide numerous parallels with Iraq, and suggest a pattern of future blunders and atrocities. Those in Britain who like to regard more recent military interventions as humanitarian might dwell on those parallels as the latest phase of the Iraq war unfolds.

British ministers' claim to be defending civilisation against barbarity in Iraq finds a powerful echo in 1950s Kenya, when Britain sought to smash an uprising against colonial rule. Yet, while the British media and political class expressed horror at the tactics of the Mau Mau, the worst abuses were committed by the occupiers. The colonial police used methods like slicing off ears, flogging until death and pouring paraffin over suspects who were then set alight.

British forces killed around 10,000 Kenyans during the Mau Mau campaign, compared with the 600 deaths among the colonial forces and European civilians. Some British battalions kept scoreboards recording kills, and gave £5 rewards for the first sub-unit to kill an insurgent, whose hands were often chopped off to make fingerprinting easier. "Free fire zones" were set up, where any African could be shot on sight.

As opposition to British rule intensified, brutal "resettlement" operations, which led to the deaths of tens of thousands, forced around 90,000 into detention camps. In this 1950s version of Abu Ghraib prison in Iraq, forced labour and beatings were systematic and disease rampant. Former camp officers described "short rations, overwork, brutality and flogging" and "Japanese methods of torture".

Guerrillas resisting British rule were routinely designated "terrorists", as now in Iraq. Britain never admitted that it was opposing a popular, nationalist rebellion in Kenya. Similarly, leftwing Malayan insurgents fighting British rule in the 1950s had strong popular support among the Chinese community but were officially called "terrorists". In secret, however, Foreign Office correspondence described the war as being fought "in defence of [the] rubber industry", then controlled by British and European companies.

But under the banner of fighting communism, British forces were given free rein in Malaya. Collective punishments were inflicted on villages for aiding insurgents. A shoot-to-kill policy was promoted, tens of thousands of people were removed into "new villages" and used as cheap labour, and British soldiers had themselves photographed holding guerrillas' decapitated heads. The idea that the revolt was ended through "winning hearts and minds" is a myth; it was crushed by overwhelming force, such as massive aerial bombing.

The brutality needed to be kept secret, a key theme in suppressing revolts. After Britain intervened to crush a rebellion in Oman in 1957, an internal Foreign Office minute stated that "we want to avoid the RAF killing Arabs if possible, especially as there will be newspaper correspondents on the spot". The British army commander in Oman later noted that "great pains were taken throughout the Command to keep all operational actions out of the press".

The reason for this was that Britain committed numerous war crimes in Oman, including the systematic bombing of civilian targets such as water supplies and farms. These attacks "would deter dissident villages from gathering their crops" and ensure "denial of water", officials stated in private. Bombing was intended to "show the population the power of weapons at our disposal" and to convince them that "resistance will be fruitless and lead only to hardship".

Britain was defending an extremely repressive regime where smoking in public, playing football and talking to anyone for more than 15 minutes were banned. Yet Harold Macmillan told President Kennedy in a 1957 telegram that "we believe that the sultan is a true friend to the west and is doing his best for his people".

As Blair and Bush claim to support democracy in Iraq, it is as well to remember that London and Washington have almost always opposed popular, democratic forces in the Middle East, preferring strong regimes capable of bringing "order".

Britain's stance on the US war in Vietnam offers other useful lessons. Just as Tony Blair poses as providing a brake on US tactics in Iraq, Harold Wilson claimed to do the same over Vietnam. Yet Britain secretly backed the US in every stage of military escalation.

In July 1965, when the US doubled its ground troop numbers in Vietnam, Wilson privately reassured President Johnson of his support for US policies "in the interests of peace and stability".

The Wilson-Johnson correspondence highlights a shocking level of connivance between No 10 and the White House to deceive the public. When the US first bombed Hanoi and Haiphong in June 1966, Wilson issued a statement disassociating the government from the bombing. Yet this statement had been passed to the US for approval while Wilson assured Johnson that "I cannot see that there is any change in your basic position that I could urge on you." The myth in Iraq that Britain is not complicit in US brutalities has its precedent in Vietnam. Declassified files show that, in 1962, Britain covertly sent an SAS team to south Vietnam under "temporary civilian status", to help train soldiers of the dictatorial regime of President Diem. Britain secretly provided arms and intelligence support to the US to improve US bombing.

Moreover, brutal US "counter-insurgency" programmes were based on prototypes developed by British advisers. Britain's "Delta Plan" for the south Vietnamese regime, described by the Foreign Office as intended "to dominate, control and win over the population" in rural areas, became the US "strategic hamlets" programme, which forced millions of Vietnamese peasants into fortified villages that resembled concentration camps.

As in Iraq, the publicly proclaimed search for peace was largely a charade. A senior Foreign Office official wrote in 1965: "The government are fighting a continuous rearguard action to preserve British diplomatic support for American policy in Vietnam. They can only get away with this by constantly emphasising that our objective, and that of the Americans, is a negotiated settlement".

These episodes highlight the gulf between what ministers have told the public and what they have understood to be the case in private. The declassified secret files point to some harsh truths about current policy in Iraq: that the war is not about what our leaders say it is (democracy), is not primarily against who they say it is (terrorists) and is not being conducted for whom they say it is (Iraqis).

Iraqis are in practice regarded as "unpeople" whose deaths matter little in the pursuit of western power; the major block on committing atrocities is the fear of being exposed and ministers will do all they can to cover them up. The public is the major threat to their strategy, which explains why they resort to public deception campaigns. If, as must be expected, atrocities now multiply in Iraq - with Britain complicit - we cannot claim we were not warned.

Mark Curtis' new book, Unpeople: Britain's Secret Human Rights Abuses, is published next month by Vintage.

© 2004 Guardian Newspapers, Ltd.