The top US commander in Iraq has suggested increasing the number of combat forces in breach of a recently signed deal for their withdrawal.

General Ray Odierno said in an interview with The Times that he would ask the White House to keep combat troops in the northern provinces of Mosul and Baqubah beyond a deadline set last year for their withdrawal by the end of June.

The general added that a joint assessment would be conducted with the Iraqi authorities in the coming weeks and a final decision over keeping or withdrawing the troops would be made by Prime Minister Nouri al-Maliki.

Under a security deal signed between Baghdad and Washington last year, combat troops are due to leave all Iraqi cities by the end of June and all other forces must be out by the end of 2011.

The agreement, which was approved after several months of negations by the Iraqi Parliament, will be put to a referendum in July.

Earlier on Thursday, tens of thousands of Iraqis held rallies to demand an end to the US occupation, on the sixth anniversary of the American invasion of the country.

Among the demonstrators were supporters of Shia cleric Moqtada al-Sadr who formerly warned against the US plans to stay in the country beyond the deadline.

Late last year, after the deal was officially signed by Baghdad, General Odierno suggested that thousands of US troops would remain in Iraqi cities.

The remarks however are in contrast with the statements made by US President Barack Obama during his surprise visit to Iraq last week.

Speaking to an audience of US troops, Obama said, "It is time for us to transfer (control) to the Iraqis. They need to take responsibility for their country."