Gordon Brown is in Baghdad for his first visit to Iraq since becoming Prime Minister.
The visit comes amid unconfirmed reports the PM is to consider a huge reduction in the number of British troops in Basra.
Reports said as many as 2,000 troops could be home by the spring. The Basra contingent could fall to just over 3,000 in the next six months, The Daily Telegraph said.
Mr Brown will hold talks with senior Iraqi politicians, including Prime Minister Nouri Maliki. He is also due to meet the US commander in Iraq, General David Petraeus.
His visit comes ahead of his Commons statement next week on the future of the British mission in Basra.
"He is going to want to discuss the developing security situation in Basra, the prospects for the Iraqis taking over and the timescale for that," one senior official said.
"This is part of the process of preparing and finalising the statement to Parliament early next week."
Britain currently has 5,000 troops stationed at Basra Airport following their pull-out from Basra Palace - their last remaining base in the city itself.
UK commanders are hoping to be able finally to hand over full responsibility for security in the city to the Iraqis in the coming weeks and months.
It is expected, however, that a British force will remain at the airport for some time to come on "tactical overwatch", ready to assist the Iraqi security forces if they run into difficulties they cannot cope with alone.
Click to view image: '102717-dsss.jpg'
|Liveleak on Facebook|