Saddam Hussein's top intelligence officials held secret talks with Osama bin Laden, US Secretary of State Colin Powell claimed yesterday.

He was setting out America's case for war with Iraq to the United Nations Security Council in New York.

Mr Powell used satellite photographs and intercepted telephone calls to spell out why the US believed Iraq was continuing to work on banned weapons programmes.

He said the US had uncovered evidence that Iraq was using a fleet of mobile production units to conceal its biological weapons programme from the UN inspectors; had tested chemical nerve agents on prisoners and was still trying to acquire materials to build a nuclear bomb.

But the most dramatic section of his lengthy presentation - lasting well over an hour - was the most detailed account yet produced of Saddam's alleged links with bin Laden's al Qaida network.

Mr Powell said that the US had evidence from an unnamed foreign intelligence agency that bin Laden had met senior Iraqi intelligence officials twice in the mid-1990s, including the head of Iraqi intelligence.

Iraq had offered chemical and biological weapons training to al Qaida associates and Iraq had helped one "militant" to acquire poisons and gases.

Nearly two dozen extremists linked to al Qaida were now based in Baghdad, co-ordinating the movement of people, money and supplies throughout the country.

Mr Powell said that members of the network had been arrested across Europe and that Manchester police officer Stephen Oake had been killed during the disruption of one of its cells in Britain.

Foreign Secretary Jack Straw said that Mr Powell had made a "most powerful and authoritative case". He effectively set a deadline of February 14 - when the UN weapons inspectors report again to the Security Council - for Iraq to co-operate and surrender its weapons of mass destruction.

"If non co-operation continues, this council must meet its responsibilities," he said.

Mr Powell told the Security Council: "We must not shrink from whatever is ahead of us. We must not fail in our duty."

However, France responded to Mr Powell's presentation by calling for a tripling of the number of weapons inspectors.

"The use of force can only be a final recourse," said foreign minister Dominique de Villepin.

Russian Foreign Minister Igor Ivanov said Iraq must provide answers to questions raised by Powell's presentation. He added: "The information will require very serious and thorough study."

In Baghdad, a senior Iraqi official called Mr Powell's speech a "typical American show complete with stunts and special effects".

* A YouGov poll for ITV News last night showed that 38 per cent of Britons had been convinced by George Bush and Tony Blair of the need for military action, as against 34 per cent in mid-January.