Prime Minister Tony Blair's spokesman said the copying did not "take away from the core argument" of the dossier, which purported to detail how Iraq is blocking United Nations weapons inspectors.

Opponents of Blair's hawkish stance on Iraq said the case of the replica report was proof the government is not playing straight in making the case for a war on Saddam Hussein.

"It just adds to the general impression that what we have been treated to is a farrago of half-truths, assertions and over-the-top spin," lawmaker Peter Kilfoyle, a member of Blair's governing Labor Party, told British Broadcasting Corp. radio.

The document, posted Monday on Blair's Web site and later released to delegates at the United Nations in New York, claimed to be based in part on "intelligence material" and to give "up to date details" of Saddam's security and intelligence network.

Britain's Channel 4 news revealed Thursday that most of the document was taken, with little alteration, from published sources, including an article by Monterey- California-based researcher Ibrahim al-Marashi that appeared last September in the Middle East Review of International Affairs.

Passages several paragraphs long are identical in the two documents. Other sections contain very minor alterations, and at least one typographical error in al-Marashi's article is repeated in the dossier.

Al-Marashi, a research associate at the Center for Nonproliferation Studies in Monterey, said he had not been approached by the British government about using his work.

"It was a shock to me," he told The Associated Press.

Al-Marashi's article looked at Saddam's security apparatus over the past three decades, and drew information that was recent at the time of publication, as well as some that was years old, al-Marashi said.

The government said its dossier was based on "a number of sources, including intelligence material," but did not give details. Among other claims, its said Iraqi security agents had bugged every room and telephone of the U.N. weapons inspectors in Baghdad and had hidden documents in Iraqi hospitals, mosques and homes.

U.S. Secretary of State Colin Powell cited the dossier on Wednesday as he addressed the United Nations with evidence of Iraq's weapons programs.

"I would call my colleagues attention to the fine paper that United Kingdom distributed yesterday, which describes in exquisite detail Iraqi deception activities," Powell said.

Blair's spokesman said the sections of the report describing the current activities of Iraqi intelligence "are largely based on intelligence material," but conceded that the section on Iraq's security structure — 10 pages of the 19-page report — drew on al-Marashi's work, "which in retrospect we should have acknowledged."

"The fact that we used some of his work does not throw into question the accuracy of the document as a whole," he added.

Opposition politicians — and some from Labor — condemned the government's sleight of hand. Blair, a staunch supporter of U.S. President George W. Bush's tough line on Iraq, has released several dossiers over the past months as evidence that Saddam Hussein's regime is harboring chemical and biological weapons.

Menzies Campbell, foreign affairs spokesman for the opposition Liberal Democrats, said the affair was "the intelligence equivalent of being caught stealing the spoons."

Labor lawmaker Glenda Jackson, who has spoken against war with Iraq, said the document "is another example of how the government is attempting to mislead the country and Parliament on the issue of a possible war with Iraq.

"And of course to mislead is a Parliamentary euphemism for lying."