John Scarlett, chairman of Britain's secretive Joint Intelligence Committee, defended the reliability of the information, even though it came from a single, uncorroborated source.
"This was a report from a single source," Scarlett told a judicial inquiry investigating the suicide of weapons adviser David Kelly, a top British scientist who took part in drafting the dossier.
"It was an established and reliable line of reporting and it was quoting a senior Iraqi military officer," he said.
Scarlett said intelligence suggested Iraq could deploy the weapons within a maximum of 45 minutes, but on average closer to 20 minutes.
Asked whether intelligence officers were unhappy about the government's use of the 45-minute claim in a September dossier that was used to justify action against Iraq, Scarlett replied, "Not at all."
"I was not aware of any unhappiness within the intelligence community about the contents in the dossier and the judgments we were making in it," he said.
But he did not reject earlier testimony that some members of the intelligence community had questioned the reliability of the information about the 45-minute claim. He said there was extensive discussion about how to word the claim, describing it as a normal part of intelligence work.
Scarlett, who played a central role in drawing up the September dossier, has become a key figure in the controversy surrounding claims that Prime Minister Tony Blair's government exaggerated the threat posed by Saddam Hussein.
The publication of the dossier, which was later quoted by President Bush and Secretary of State Colin Powell in their own indictments of Iraq, was a key moment in the build up to war.
Scarlett said Tuesday he was in charge of preparing the dossier, although he did receive advice on wording and presentation from Blair's main spokesman, Alastair Campbell.
A BBC report claiming that Campbell had the 45-minute claim inserted in the dossier to make it stronger ignited a political storm that has dominated British politics for three months. Campbell has denied the report.
According to the Times of London, Scarlett testified that Campbell asked for the language to be "tightened."
Scarlett said Tuesday that Campbell gave advice, but insisted he was never subjected to any political pressure. "None at all," he said.
But he did say that intelligence agencies were asked at the last minute to find new intelligence to bolster the report.
Lord Hutton, the senior appeals judge directing the inquiry, has called Blair to testify on Thursday and Defense Secretary Geoff Hoon on Wednesday.
Tuesday's hearing began with testimony from lawmaker Andrew MacKinlay, a member of Blair's ruling Labor Party who sat on a parliamentary committee that questioned Kelly before his death.
Kelly, a widely respected authority on weapons of mass destruction, was identified as the source for a British Broadcasting Corp. report questioning the integrity of the dossier — in particular its claim that Saddam's forces could deploy chemical or biological weapons within 45 minutes.
After the Defense Ministry made Kelly's name public, the 59-year-old microbiologist and former U.N. weapons inspector in Iraq committed suicide. The BBC later confirmed he was the unidentified official quoted in its report.
Over the weekend, 9,000 pages of documents from the Hutton inquiry were published on its Internet site, including private e-mails and memos from government officials. They showed that Blair and his top advisers had discussed whether to identify Kelly, and worried about what would happen to him if they did.
Three days before his body was found, Kelly told the Foreign Affairs Committee that he believed he wasn't the main source for the BBC story by reporter Andrew Gilligan.
MacKinlay told Tuesday's hearing that Kelly had convinced him "very impressively indeed" that he was not the source for the BBC story. He also described as "absolutely outrageous" an e-mail Gilligan sent to some members of the Foreign Affairs Committee suggesting lines of questioning for Kelly.
In the months that have passed since the war without a single reported discovery of illegal weapons, both Blair and the Bush administration have come under pressure for the claims they made before the war.
President Bush has recanted a charge from his State of the Union that Iraq sought uranium in Africa. Unmanned drones appear to have been built for reconnaissance rather than WMD attacks. Scientists from the State Department have questioned whether two captured Iraqi trailers are mobile bioweapons factories, as the CIA insists.
Intelligence officers have accused the administration of politicizing intelligence or ignoring doubts about it.