A prominent activist in Bahrain has been detained by authorities after a raid on his home.

The family of Nabeel Rajab and an activist group, Human Rights First, say he was taken into custody early on Monday morning.

The raid was not immediately reported by the state-run Bahrain News Agency nor by police. Officials could not be immediately reached for comment.

Rajab, who is president of the Bahrain Center for Human Rights, received a pardon from King Hamad bin Isa Al Khalifa in July 2015 over comments that previously angered the Sunni-ruled island's government.

Bahrain is an important Western ally in the Gulf, and hosts the U.S. Navy's 5th Fleet. It's seen low-level unrest since it put down 2011 protests by its Shiite majority and others seeking more political freedoms.