The UN's chief Kofi Annan has warned Britain that it would be "unwise" to invade Iraq.

The secretary general told Tony Blair during an hour-long meeting in Downing Street on Monday that he believed the US had yet to decide whether to end Saddam Hussein's rule.

His comments followed weeks of fevered speculation, particularly in the US media, that President Bush planned to deal with the unfinished business of the Gulf war as part of the war on terrorism.

"I don't think Washington has taken any decision yet as to what to do about Iraq. But I myself am on record as saying that any attack on Iraq at this stage would be unwise," Annan said.

Also on the agenda was a follow-up to Blair's Africa tour last month as well as the role of British forces as part of ISAF in Afghanistan and the deteriorating situation in the Middle East.

Downing Street described the meeting as "positive and upbeat".

Annan also held a meeting with chancellor Gordon Brown and deputy prime minister John Prescott to discuss global poverty ahead of the Financing for Development Conference in Monterrey.

Prescott said fighting poverty would be a vital part of winning the war on terrorism. "The global alliance is winning the war against terrorism, but we must also win the peace," he said. Our commitment has never been in doubt.

"Over recent months the chancellor and I have taken every opportunity to discuss with other world leaders the key issues that must be addressed in Johannesburg.

"The developed world must be prepared to take on the responsibility of tackling poverty, establishing sustainable development and protecting the environment."