The coalition should have foreseen that its occupation of their country would be resented by some Iraqis, particularly Sunni Arabs and some Shia nationalist elements, the Commons Defence Committee said.

As a result of its failure to appreciate the potential danger from insurgents, the coalition was confronted with the most challenging post-conflict campaign in 60 years. Moreover, until Iraq’s security could be guaranteed by its own forces, British troops were likely to be invited by Baghdad to stay. “This may be a substantial period of time,” the MPs said.

The committee joins a long list of organisations and agencies which have attacked the coalition’s prewar planning.

“It is difficult to avoid concluding that the coalition, including British forces, were insufficiently prepared for the challenge represented by the insurgency,” its report said.

Before the war, there had been a wide range of predictions about the likely post- conflict situation in Iraq. Yet, despite extensive planning by the coalition, the warnings were not reflected in the blueprint for action after the combat phase was over.

The MPs made a point of praising the British troops “for their approach to counter- insurgency in their areas of operation” which had led to a “more permissive environment” in southern Iraq.

However, the coalition as a whole had believed that “ordinary Iraqis would welcome liberation from dictatorship, and they seemingly overestimated the ease of transition from war to post-conflict rehabilitation”.

The committee said that the coalition strategists were guilty of five key planning misjudgments: they failed to anticipate that many Iraqis would seek actively to take advantage of the power vacuum after the combat phase; they underestimated the insurgency; they seemed unable to decide what to do about the Iraqi military and security forces; they failed to plan adequately for the scope of the reconstruction; and they underestimated the number of troops needed during Iraq’s transition.

The Ministry of Defence admitted in a memorandum to the committee that limited effort had been spent planning for contingencies, including the prospects of an insurgency. The memo said: “There was very limited intelligence . . . an insurgency on the scale that subsequently developed was not foreseen before the end of major combat operations.”

Even now, the MPs said, there was considerable discrepancy in the estimates of the size of the insurgency, with the CIA reportedly saying 50,000, and the commander of US Central Command putting the total at about 5,000.

The committee said: “The CIA’s figure probably includes non-combat supporters such as couriers, spies, etc. (The US Central Command chief) General John Abizaid’s figure probably counts only ‘trigger-pullers’.”

Asked to give its own estimate, the MoD declined.

• The pilot of the RAF Hercules transport aircraft that crashed in Iraq killing ten servicemen sent a mayday distress signal eight minutes after take-off, an inquest in Trowbridge, Wiltshire, was told. The coroner released the bodies for burial and the hearing was adjourned.

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