US Democratic presidential candidate Barack Obama said yesterday he was committed to a 16-month timetable for a US military withdrawal from Iraq, after a trip in which he met Iraqi leaders and US officials.

Mr Obama was speaking in the Jordanian capital as part of a tour of the region in which he has sought to shift the focus of US military efforts from Iraq to Afghanistan, where al Qaeda and the Taliban are resurgent.

The question of when to withdraw some 147,000 US troops in Iraq overshadowed the first term senator's trip. Mr Obama has made his opposition to the US-led invasion of Iraq in 2003 a centrepiece of his election campaign.

"What I have proposed is a steady, deliberate draw down over the course of 16 months," he told a news conference in Amman.

Mr Obama has said the draw down would enable more troops to be deployed in Afghanistan, where insurgent attacks in the past two months have killed more US soldiers than in Iraq. He described the situation in Afghanistan as "perilous and urgent" and said al Qaeda and the Taliban were planning more attacks in the United States.

"In Afghanistan and the border region of Pakistan, al Qaeda and the Taliban are mounting a growing offensive against the security of the Afghan people and increasingly the Pakistani people, while plotting new attacks against the United States," he said.

Progress in boosting stability and security in Iraq would come from reconciling Iraq's feuding political groups, he said.

In London, British Prime Minister Gordon Brown told Parliament he expected to see a "fundamental change of mission" for British troops in southern Iraq early next year.

The improved security situation in the Basra region meant the 4,100 British troops based there would focus on training Iraqi troops before gradually withdrawing from Iraq, he said.