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

German Chancellor Angela Merkel said it would be “particularly sickening” if he were proven to be a refugee.

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

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