Almost all of the UK's 4,100 troops will leave Iraq by July 2009
A vote in the Iraqi parliament on a resolution that would allow non-US forces to remain in the country after the end of the year has been postponed.
Speaker Mahmoud al-Mashhadani called for the delay after some MPs demanded his resignation over a separate matter.
Failure to resolve the issue before the troops' current UN mandate runs out on 31 December would mean they had no legal basis to stay in Iraq.
Parliament may reconvene to vote on the issue on Tuesday.
On Saturday, MPs rejected a bill which would have given the 6,000 non-US troops that legal basis.
A compromise was reached to vote on a resolution - which requires only a simple majority of MPs to be passed. But the session of parliament was postponed amid the row over the speaker.
Shia and Kurdish lawmakers want him to resign after he failed to control a shouting match over the journalist who threw his shoes at President George W Bush, the Associated Press news agency said.
Iraq's governing parties had been optimistic that the resolution would be passed.
The US has already struck a separate security pact to keep troops in Iraq to 2011.
The UK says it plans to withdraw all but 400 of its 4,100 troops from Iraq by the end of July. Australia, Estonia, Romania and El Salvador also have small contingents in Iraq.
The resolution would authorise the Iraqi government to sign separate bilateral deals with each nation which would give them the legal protection their troops need to remain beyond the end of the year, the BBC's Caroline Wyatt reports from Baghdad.
It is a way of avoiding another rejection of the draft law, our correspondent adds.
NON-US FORCES IN IRAQ
UK - 4,100
Australia - 1,000
Romania - 500
El Salvador - 200
Estonia - 40
Some MPs said they had rejected the draft because its terms were not as strict as the pact governing US forces agreed this month.
Others, loyal to the radical Shia cleric Moqtada Sadr, said they wanted the foreign troops to leave Iraq when the UN mandate ends.
There was also some confusion in the 275-member assembly about what was being voted on, after an earlier rowdy session of parliament was suspended, our correspondent adds.
Earlier in the week, UK Prime Minister Gordon Brown announced that the UK planned to withdraw its troops from southern Iraq by the end of July 2009, as envisaged by the draft law.
Military operations will conclude in May and the vast majority of UK troops will then leave. About 400 personnel will remain to train Iraqi forces, including the navy.
US troops will be moved to Basra, where the bulk of the UK troops have been stationed.