The activities of Al Qaeda in two of Iraq’s most troubled cities could keep U.S. combat troops engaged beyond the June 30 deadline for their withdrawal, the top U.S. commander in the country has warned.

U.S. troop numbers in Mosul and Baqubah, in the north of the country, could rise rather than fall if necessary, General Ray Odierno told The Times in his first interview with a British newspaper since taking over from General David Petraeus in September.

He said that a joint assessment would be conducted with the Iraqi authorities in the coming weeks before a decision is made.

Combat troops are due to leave all Iraqi cities by the end of June. Any delay would be a potential setback for President Obama, who has pledged to withdraw all combat forces from Iraq by August 2010 as he switches his focus to Afghanistan.

The ultimate decision on keeping or withdrawing troops would be taken by Nouri al-Maliki, the Iraqi Prime Minister, handing him a major dilemma given the desire by most Iraqis for the U.S. military to leave the country.

Tens of thousands of supporters of Moqtada al-Sadr, the anti-American Shia cleric, marched through Baghdad yesterday, the sixth anniversary of the fall of the capital, to demand the withdrawal of U.S. forces.

General Odierno, 54, said that he was also concerned about the risk of renewed conflict between Arabs and Kurds in northern Iraq, where tensions are rising over the ownership of territory. He also cited the “very dangerous” threat posed by Iranian-funded militants who appear to be styling themselves on Lebanon’s Hezbollah.

Click here for more on this story from the Times of London.