MANAMA, Bahrain (AP) - Bahrain's interior ministry says an explosion has wounded seven policemen in what is described as a "terrorist" attack in the violence-wracked Gulf kingdom.

Thursday's statement says at least two policemen are in critical condition. It says a homemade device went off late on Wednesday in Bani Jamra, the site of frequent clashes about 10 kilometres west of the capita, Manama.

Police have been targeted before in the more than two-year unrest in the strategic island nation, which is home to the US Navy's 5th Fleet. But the latest blast is among the most police casualties in a single attack.

More than 60 people have been killed since Bahrain's majority Shiites began an Arab Spring-inspired uprising for a greater political voice in the Sunni-ruled nation.