US Secretary of State Colin Powell, who made the case to the world that pre-war Iraq had stocks of chemical and biological weapons, said on Monday he now thought these will probably never be found.

"I think it's unlikely that we will find any stockpiles," Powell told lawmakers when asked about the intelligence behind his February 5, 2003, UN Security Council speech laying out US arguments for the war with Iraq that began six weeks later.

Powell's latest comments appeared to be his most explicit to date suggesting that the central argument for President Bush's decision to invade Iraq -- the belief it possessed weapons of mass destruction -- was flawed.

As early as January Powell said it was an "open question" whether or not such arms would be found and he conceded the possibility Iraq might not have had any when the war began.

Bush himself had often said that even if no such weapons are found he did the right thing in invading Iraq in March 2003 and toppling Iraqi leader Saddam Hussein, arguing that the country has been liberated from brutal dictatorship.

US officials have also said that whether or not it had stockpiles in 2003, Iraq was a threat because it had possessed and used chemical weapons in the past, notably to kill 5,000 Iraqi Kurds in the town of Halabja in 1988.

The war in Iraq, in which more than 1,000 US troops have died, and the violent insurgency that has developed since the US invasion are a major issues in Bush's reelection battle against Democratic nominee Sen. John Kerry of Massachusetts.

Powell made his comments as Charles Duelfer, the CIA-named leader of the hunt for weapons of mass destruction in Iraq, is working on a report about his findings that was expected to be completed in the next few weeks.

Duelfer's predecessor, David Kay, said as he left the post in January that he believed there were no large stockpiles of weapons of mass destruction when Washington went to war.

While he had reservations about the state of Iraq's efforts to obtain nuclear weapons when he spoke before the UN Security Council in February 2003, Powell insisted at that time that it had stocks of both biological and chemical weapons.

"There can be no doubt that Saddam Hussein has biological weapons and the capability to rapidly produce more, many more," Powell said then, at one point holding up a vial of simulated biological agent -- an image broadcast around the world.

"Our conservative estimate is that Iraq today has a stockpile of between 100 and 500 tons of chemical weapons agent," he said at the time.

(China Daily via agencies September 14, 2004)