Former DR Congo leader arrested
He is facing charges of war crimes and crimes against humanity.
Jean-Pierre Bemba, who fled Congo last year, was detained near Brussels late on Saturday after the International Criminal Court issued a warrant.
Mr Bemba is wanted for alleged atrocities committed by his forces in the Central African Republic in 2002.
He went into exile after being accused of high treason in his home country.
He was accused of refusing to disarm his militia after his defeat in presidential elections in 2006, and of unleashing violence in the capital, Kinshasa.
Mr Bemba has always denied the charges.
The successful businessman was one of four vice-presidents in a transitional government in the war-torn African nation between 2003 and 2006.
He was leader of the rebel group, the Movement for the Liberation of Congo, which later became a political party.