Tuesday's vote on Iraq will be parliament's most important moment for "many years", Jack Straw has told MPs.

Making a late night statement to the Commons, the foreign secretary said that the "intense diplomatic activity" seeking international consensus on the crisis had come to an end.

Clare Short, David Blunkett, Gordon Brown and Tony Blair were all absent from the chamber as the speech was delivered.

Having spoken with his Spanish, American, Russian and Chinese counterparts on Monday, Straw said it had become apparent that there was no prospect for a second United Nations resolution authorising military action should Saddam Hussein fail to comply with security council demands.

Straw said the government had then decided to end the search for a second resolution.

He said that no country thought Iraq had met its international obligations.

And the foreign secretary then placed the blamed for the failure to reach consensus squarely at the door of French ministers.

"It was my belief up to about a week ago that we were close to achieving the consensus which we sought on the further resolution," he said.

France's pledge to veto any resolution containing any ultimatum "inevitably created a sense of paralysis in our negotiations".

"I deeply regret that France has thereby put a security council consensus beyond reach."

He said that calls for delays in military action amounted to an attempt to re-write resolution 1441, sending the message that the UN would not enforce its ultimatums.

"As a result of Saddam Hussein's persistent refusal to meet the United Nations' demands, and the inability of the security council to adopt a further resolution, the Cabinet has decided to ask the House's support the United Kingdom's participation in military operations, should they be necessary, with the objective of ensuring the disarmament of Iraq's weapons of mass destruction and thereby the maintenance of the authority of the United Nations," Straw told MPs.

"The debate tomorrow will be the most important in the House for many years."

He warned that allowing more time for inspections "cannot produce the disarmament of Iraq...it can only bring comfort to tyrants and emasculate the authority of the United Nations".