Two explosions occurred late Sunday in the coalition-controlled zone which includes the Al Rashid Hotel (search), but the location had not been determined, the U.S. military said.

However, an Iraqi policeman, speaking on condition of anonymity, said that an assailant fired a rocket propelled grenade at a U.S. convoy next to al-Mansour Hotel (search), located about a mile northeast of the Al Rashid. He said there were no casualties.

Immediately after the attack, two U.S. armored personnel carriers and a number of Humvees (search) cordoned the area off and prevented journalists from approaching.

The blasts, which could be heard across the Tigris River in the center of the city, occurred after 9 p.m., more than 15 hours after a rocket attack against the Al Rashid in which an American colonel was killed and 15 other people were injured.

The area, known as the "green zone," also includes the coalition headquarters at one of Saddam Hussein's palaces and the Convention Center, which includes the military's press office.