WASHINGTON, Nov 19: Outgoing US Secretary of State Colin Powell's announcement earlier this week that Iran could be developing nuclear-capable missiles was based on an "unvetted, single source," The Washington Post said on Friday.

The intelligence, which two US officials said had not been verified, could be significant if true but an embarrassment if not, reminiscent of Powell's February 2003 UN speech about Iraq's alleged weapons of mass destruction, which was based on dubious intelligence and which so far has proved untrue.

The officials told the daily that the intelligence was stamped "No Foreign," meaning it was not to be shared even with US allies, although they said President Bush shared portions of it with British Prime Minister, Tony Blair, last week.

Mr Powell, in Santiago for an APEC summit this weekend, said on Wednesday that he had "seen some information that would suggest" that Iran was seeking to adapt its missiles to carry nuclear warheads - they have "been actively working on delivery systems," he said.

The information in Powell's comment was drawn from a "walk-in" source, who provided US intelligence with 1,000 pages of alleged Iranian drawings and technical documents, including modifications to ballistic missiles to carry nuclear weapons, one official with access to the material told the daily.

The officials, who asked not to be identified but agreed to talk with the daily about information already disclosed by Mr Powell, said the source was not previously known to US intelligence.

They said the Central Intelligence Agency remained unsure about the authenticity of the documents and how they came into the informant's possession. The officials did not know the identity of the source or whether he was connected to an Iranian exile group which made new accusations about Iran's alleged nuclear weapons ambitions in Paris on Wednesday.

They said the lack of certainty about the source had kept them from talking publicly about the information and that Powell's comments had caught them by surprise and even angered some of them.

Mr Powell, who is to be succeeded by national security adviser Condoleezza Rice during Bush's second term in office, has been described by some newspapers as the moderate, "odd man out" in a hawkish Bush administration and has often been in hot water for his comments.

The Washington Post quoted other unidentified sources as saying that the US government, to assuage concerns over Iran, told some European diplomats that Mr Powell had misspoken in releasing information that had not been verified. Iran on Sunday agreed with Britain, France and Germany to freeze uranium enrichment-related activities. -AFP