Rebel Labour MPs have failed in a bid to stage a symbolic show of defiance over the government's Iraq policy.
The Lib Dems called for phased withdrawal
After a six-hour debate on Iraq and the Middle East, they were expected to force a symbolic vote to show their opposition to Tony Blair's policy.
But their attempts to force a vote were scuppered after failing to anticipate that the government would not put forward any tellers for the vote.
During the debate Mr Blair came under repeated fire for failing to attend.
But speaking at prime minister's questions, before the debate, Mr Blair had criticised a Lib Dem call for UK troops to be brought home by October.
He said setting an "arbitrary timetable" for troop withdrawal was "a policy which, whatever its superficial attractions may be, is actually deeply irresponsible".
But he was heavily criticised by many MPs for not staying on and opening the debate, instead choosing to address business leaders nearby.
Scottish National Party leader Alex Salmond asked: "Why was he so anxious to talk us into this disastrous war but so reluctant to explain how we are going to get out of it?"
Foreign Secretary Margaret Beckett said Mr Blair would report back to the Commons once Operation Sinbad, currently under way in Basra, was complete.
She said no prime minister had put themselves before "the scrutiny of Parliament" more than Mr Blair.
The call for a phased withdrawal of British troops, between May and the end of October, was made by Liberal Democrats leader Sir Menzies Campbell, who opposed the invasion in 2003.
He told the debate: "No-one can accuse the United Kingdom of cutting and running after four years in which we have tried, we have tried to the best of our ability, to fulfil the objectives of the United Nations resolution."
He added: "I don't think it's any longer reasonable or legitimate to ask our armed forces to bear this burden."
But Mrs Beckett said: "We are not setting and never have set and never will set, because we think it would be dangerously irresponsible, a specific date, a specific deadline, a specific timeline, we will judge on the conditions."
However, she told MPs that British troops could hand control of Basra to local authorities this spring.
For the Conservatives, who backed the war, Shadow Foreign Secretary William Hague called for a "high level" Privy Council inquiry into its conduct.
He also expressed some concern at US plans to send extra troops to Baghdad and Anbar province. "Aren't we justified, given that previous attempts to flood Baghdad with larger numbers of troops have not achieved their objectives, to be somewhat sceptical about the deployment of 20,000 additional US troops, however much we may hope they will succeed?"
Several Labour backbenchers spoke out against the government's policy, including former ministers Frank Dobson and Peter Kilfoyle.
Mr Dobson said parts of Iraq were now in "murderous chaos", adding: "There will be no fairytale ending to the occupation whether it's this year, next year or in five years' time and, that being the case, my own sad conclusion is the sooner we withdraw the better."
And George Galloway, of the anti-war Respect Party, accused the government of trying to "lull us into sleepwalking into a coming conflict with Iran".
He said if Iran was attacked, British soldiers in a "thin red line in the sand" in southern Iraq would be the "first to suffer."
At the end of the debate there was confusion among anti-war MPs, who complained that they had not been allowed to table their opposition to the conflict in Iraq.
They accused the government of refusing to provide tellers at the end of the debate, so that no vote could be taken.
But Parliament-watchers said there was no need for the government to put forward tellers and said the war critics should have anticipated the possibility that that would happen.