The UK prime minister met chief weapons inspector Hans Blix and the head of the International Atomic Energy Agency Mohamed ElBaradei for talks in London on Thursday.
"
The message coming from the Security Council is very clear, that
Iraq is not co-operating fully
"
Mohamed ElBaradei
The meeting came as politicians and diplomats around the world consider the latest evidence put forward by the United States to support its claims that Iraq is defying demands to disarm.
On Wednesday, US Secretary of State Colin Powell presented tape recordings, satellite photographs and intelligence data showing Baghdad's "evasion and deception" in the face of UN weapons inspections.
But it has been rejected by Iraq as an attempt to sell the idea of war without any moral or legal justification.
Message
Leaving the talks with Mr Blair, Mr Blix said Iraq continued to co-operate on the "process" of the inspections, such as granting access.
But he said the Iraqis were still failing either to present forbidden items to be destroyed or show evidence they had been destroyed already.
"I hope at this later hour they will come to a positive response," he said.
He warned that without more co-operation, the inspectors would not be able to deliver the report they wanted at the Security Council on 14 February.
Mr ElBaradei, who says war is not inevitable, said their visit to Baghdad this weekend was crucial.
"The message coming from the Security Council is very clear: that Iraq is not co-operating fully, that they need to show drastic change in terms of co-operation," he said.
Maintaining pressure
Later, Foreign Secretary Jack Straw echoed the stance taken by Tony Blair at Thursday morning's cabinet meeting.
"The issue before Iraq now and before the security council is not one of more time for inspectors ... nor of more inspectors" said Mr Straw.
"It is about much, much more cooperation from the Iraqi regime."
Mr Powell warned the special session of the UN Security Council against any further delay in tackling what he called Iraq's chemical, biological and nuclear arms ambitions.
The prime minister's spokesman said Mr Blix and Mr ElBaradei were acutely aware that Mr Blair and US President George W Bush were rapidly losing patience with the inspections process.
The spokesman added: "Saddam has to realise he cannot long-finger this any more. Time's up."
Air package
In a further development, Defence Secretary Geoff Hoon announced another 100 RAF planes are to be sent to the Gulf region ready for action.
He told MPs 7,000 extra personnel are to be deployed, bringing the UK's overall contribution to 42,000.
Mr Blair and Mr Straw also held talks on Thursday with Iranian Foreign Minister Kamal Kharrazi.
Iran has been identified by President Bush as part of an "axis of evil" alongside Iraq and North Korea.
"
The facts and Iraq's behaviour show that Saddam Hussein and his
regime are concealing their efforts to produce more weapons of mass
destruction
"
Colin Powell
But the allies are seeking to ensure Iran does nothing to obstruct any future military action against Iraq.
Mr Straw made similar diplomatic overtures by meeting Mr Kharrazi ahead of the bombing of Afghanistan.
He said there had been a "very good dialogue" on a number of issues, including the Iraq crisis, during Thursday's talks.
Mr Kharrazi said that as one of Iraq's neighbours, Iran was concerned about the possible repercussions of war, such as an influx of refugees.
The weapons inspectors should be given more time and the Iraqi regime "urged more fully" to comply with UN resolutions, he said.
On Wednesday, Mr Straw gave Saddam Hussein an effective deadline of 14 February to show he will co-operate with UN demands to disarm.
Shadow foreign secretary Michael Ancram disagreed with those who say the US evidence is not credible and said Mr Powell had showed how terrorists were probably learning technology from Iraq.