Britain's foreign secretary and other senior officials warned Prime Minister Tony Blair a year before the invasion of Iraq that chaos could follow the toppling of President Saddam Hussein, a newspaper reported on Saturday.

The Daily Telegraph said that Foreign Secretary Jack Straw sent a letter marked "secret and personal" to Blair in March 2002 warning that there were no preparations for what might happen after an invasion.

The Foreign Office declined to comment directly on the report but said in a statement that Iraq was moving toward a democratic future for the first time.

Disclosure of the letter, at a time of escalating violence in Iraq, could prove to be damaging to Blair politically, with elections in Britain likely next year. It also illustrates the depth of concern in Blair's government over joining the U.S.-led invasion in March 2003.

"No one has satisfactorily answered how there can be any certainty that the replacement regime will be any better," Straw wrote, according to the newspaper.

Blair defended his position at a news conference on Saturday.

"The idea that we did not have a plan for afterwards is simply not correct," he said.

"We did, and indeed we have unfolded that plan, but there are people in Iraq, outsiders as well as former regime elements, who are determined to stop us. That's why it is all the more important that we carry on until we win it, and we will."

The opposition Conservative Party said the document revealed a lack of a comprehensive reconstruction plan for Iraq. The Conservatives backed Blair on the war but later said their support had been based on bogus intelligence information.

"The assurances given to us by both the prime minister and Jack Straw that such a plan was in hand were clearly misleading," Michael Ancram, the Conservative Party foreign affairs spokesman, said on Saturday.

The Telegraph also reported that senior ministerial advisers warned in a "Secret UK Eyes Only" paper that success would only be achieved if the United States and others committed to "nation building for many years."

"The greater investment of Western forces, the greater our control over Iraq's future, but the greater the cost and the longer we would need to stay," the paper reportedly stated.

Blair built his case for war on the basis that Iraq possessed banned weapons of mass destruction (WMD), although no such weapons have been found since Hussein was overthrown.

The Daily Telegraph reported that British officials believed that President Bush instigated the war because he wanted to complete his father's "unfinished business."

"Even the best survey of Iraq's WMD program will not show much advance in recent years," a Foreign Office policy director said, according to the newspaper.

Bush's father, former president George H. W. Bush, oversaw the 1991 Persian Gulf War, when a U.S.-led military coalition forced occupying Iraqi forces out of neighboring Kuwait, but did not then drive Hussein from power.

Foreign Secretary Straw's letter cited poor planning.