A commission set up to advise the White House on Iraq is reported to have recommended big changes to US strategy.

One of the options said to have been given serious consideration by the Iraq Study Group, headed by former Secretary of State James Baker, is the withdrawal of large numbers of US troops from Iraq.

The other option - reported to have been studied by the group - is that the US might issue invitations to Syria and Iran to come into Iraq in order to help stop the fighting there.

The group is due to publish its report next month.

Meanwhile, US President George W Bush has assured Iraqi Prime Minister Nuri al-Maliki that the US has not set any deadline for his government to control sectarian violence and still supported his leadership.

Mr Maliki raised concerns about a timeline, saying such rumours undermined confidence in the Iraqi government and inspired terrorists, during a 15-minute telephone call initiated by Mr Bush, a White House spokesperson said.

The war in Iraq, in which about 2,750 American troops and tens of thousands of Iraqis have been killed, has dragged down Mr Bush's popularity before elections in which his Republican Party is fighting to keep control of Congress.

Mr Bush has insisted that US troops will not withdraw until Iraqis are able to take over security.