LONDON -- Prime Minister Tony Blair's communications chief acknowledged Wednesday that the government made a mistake when it used material from a graduate thesis posted on the Internet to help build a case for military action in Iraq.
The admission could elicit new calls for Blair to get troops out of the region, especially after six British military policemen were killed Tuesday in the southern Iraqi city of Basra.
The research formed part of a file drawn up to support government claims that Iraq had weapons of mass destruction.
Alastair Campbell called the mistake "regrettable" and said it occurred when the information was passed from the Foreign Office research department to the Communications and Information Center, which was collating material from several intelligence sources. An official there added it without attribution.
Campbell told the Foreign Affairs Committee, a parliamentary panel investigating government claims about Iraqi weapons of mass destruction, that he -- and Blair -- believed the information was from government sources.
The committee is focusing on two intelligence dossiers published by Blair's office setting out its case on the threat from alleged Iraqi chemical, biological and nuclear weapons.
The failure of coalition forces to find weapons of mass destruction since the war ended has put Blair on the defensive, though he has insisted that he believes they will be found.
Blair had told the House of Commons that the document was "entirely accurate," even though he was not aware that parts of it were taken from a student's thesis when he published it.
Blair came under pointed questioning from lawmakers, including members of his Labor Party, about how long British troops would remain in Iraq following the attack in Basra, the deadliest involving British troops in Iraq.
Jon Owen Jones, a Labor lawmaker, told Blair that Britain "desperately requires an exit strategy" from Iraq.
Blair said the British troop requirement had already been reduced from 46,000 there during the conflict to 14,000 now. "Exactly when those troops can come home I cannot be sure," he said.
"Our exit strategy has to be a strategy based on making sure that we maintain our pledge to help Iraq be rebuilt as a stable and prosperous country because if it is not rebuilt in that way, if it were to continue under the type of regime that Saddam Hussein represented, then it would continue to be a threat to the region and the wider world," he added.
Blair expressed his condolences for the deaths of six soldiers from the Royal Military Police, whose bodies were recovered Tuesday from the town of Majar al-Kabir, where they had been helping train local police.
Gunmen killed the six after a violent demonstration that left four Iraqi civilians dead. The Iraqis were enraged by the deaths of their countrymen at the hands of British soldiers.
The Ministry of Defense declined to comment on how the soldiers died, but a British Army spokesman in Basra said they were murdered in an unprovoked attack.
"The attack on the UK forces at Majar al-Kabir was unprovoked," British Army Lt. Col. Ronnie McCourt told Sky News TV. "The six military policemen who were trying to retrain the local police were murdered, as far as we're aware, in the police station.
"The enemies of peace have claimed that the United Kingdom forces are conducting violent searches of Arab homes and have not respected property. This is simply not true."
Blair won some support from the opposition Conservative Party, whose leader Ian Duncan Smith said the "incident should serve only to reinforce our resolve to bring peace and the rule of law to Iraq."
Blair said the violence showed the security situation in Iraq was serious and pledged further efforts to bring stability.