US Marines searched rooms at the central Baghdad hotel that is home to most of the foreign journalists in the city, apparently taking some people into custody.

Spokesman Sgt Jose Guillen confirmed that American troops had entered the Palestine Hotel, but declined to give details of the operation.

"This building wasn't 100% safe and we are making sure it is," he said. "There weren't any gunshots or anything but intelligence thought it wasn't 100% safe."

It was unclear how many rooms were searched in the 18-storey hotel, which overlooks the River Tigris from the eastern banks.

CNN television producer Linda Roth said she opened her door to find armed Marines, who ordered her to get down while they searched the room without explanation.

"There was definitely tension," she said. "They were definitely looking for someone." After the Marines left her room, she said she saw three men being guarded by US troops.