(Adds details of debate, quotes) By Sophie Walker LONDON, Jan 24 (Reuters) - British Prime Minister Tony Blair said on Wednesday it would be "deeply irresponsible" to set an arbitrary deadline for pulling British forces out of Iraq. In response, opposition parties tore into Blair during a parliamentary debate on British policy in the region, deriding his rationale for going to war, the lack of post-war planning -- and his decision not to attend the rare formal session on Iraq. Britain has some 7,100 troops in southern Iraq. Blair, undermined politically by his support for the U.S.-led war in Iraq, is under increasing pressure to name the date soldiers can start to come home before he steps down later this year. "It is not acceptable ... that the prime minister, having been so keen to lead these debates in the run-up to the war ... now prefers, with the whole issue in the balance and 130 British lives lost in Iraq, to skulk out of this chamber," Conservative spokesman on foreign affairs William Hague said. Earlier, responding to a proposal by the Liberal Democrat party to bring troops home by October, Blair said this would send a disastrous message to the insurgents British forces are battling in Basra in southern Iraq. "For us to set an arbitrary timetable -- not attached to the conditions in Iraq, simply saying that we will pull British troops out in October come what may -- would send the most disastrous signal to the people that we are fighting in Iraq. "It is a policy that, whatever its superficial attractions may be, is actually deeply irresponsible," he said. President George W. Bush urged a rebellious Congress on Tuesday to back his plan to send an additional 21,500 U.S. troops to Iraq to try to restore order in Baghdad. BLASTED Opening the Iraq debate in London, Foreign Secretary Margaret Beckett said the government backed the aim of the U.S. and Iraqi governments for all 18 Iraqi provinces now under coalition control to be handed back by November. "It is our present view, and the view of the Iraqi government, that if things continue as they are, we may well be in a position to hand over responsibility ... for all the provinces by November and certainly for Basra in the spring," Beckett told parliament. Beckett also said the government remained committed to making progress in peace talks to resolve the "festering sore" of the Israeli-Palestinian conflict. She said Britain was pressing Iran and Syria to participate in a positive way to long-term stability in the Middle East. That stance was blasted by Labour MP Frank Dobson, who said Britain's participation in the "foolish, stupid war in Iraq" had affected its ability to influence events in the Middle East. Menzies Campbell, leader of the Liberal Democrats, said his party had been right to say the war was illegal. No weapons of mass destruction were found, he said, suggesting the main point of the war had been regime change. Government officials say British operations aimed at preparing for the handover of security in Basra to Iraqi authorities could be wound up in February. Blair has said he will brief parliament on British forces' future strategy when the operation in Basra is over.
