Updated

Police say they are interrogating four suspected Irish Republican Army members over the discovery of a bomb in a car in the Northern Ireland city of Londonderry.

Police intercepted an apparent bomb in transit hours ahead of Friday's planned visit of U.S. Secretary of State Hillary Clinton to Belfast, 80 miles (130 kilometers) away. Clinton was expected to meet the Protestant and Catholic leaders of Northern Ireland's five-year-old unity government, the central achievement of the U.S.-brokered Good Friday peace accord of 1998.

Witnesses said a police vehicle rammed the IRA suspects' car, disabling it. Police said they arrested three men in the car and a fourth nearby. They declined to specify the bomb's size.

Most IRA members renounced violence and disarmed in 2005, but several splinter groups remain active.