German police are investigating a "probable terrorist attack" after a man ploughed a lorry into a Christmas market in the heart of Berlin, killing 12 people and injuring 48.

The driver, reportedly a Pakistani asylum seeker who entered Germany last year, is being questioned.

German media say police have searched a refugee shelter at a Berlin airport where he was believed to be staying.

He was reportedly known to police for minor crimes, but not terror links.

Politicians had avoided branding the bloodshed a terror attack in the hours immediately following, but Interior Minister Thomas de Maiziere told ARD television, "there are many things pointing to one".