London police say two of the city's busiest bridges have been partially closed after a suspected World War II bomb was found in the River Thames.

The Metropolitan Police force says officers were called Thursday afternoon "to reports of suspected World War II ordnance in the river."

Police say roads in the area have been closed, including northbound lanes of Waterloo Bridge and Westminster Bridge, near the Houses of Parliament.

The force says specialist officers are assessing the device.

London was heavily bombed by Nazi Germany during the war, and unexploded munitions are still sometimes found.