A Groningen policeman is recovering after being stabbed in the face by two young men during a routine curfew check on the Van Houtenlaan in the south of the northern city on Wednesday evening.

The youths, described as white and wearing dark clothes, were stopped by the officer and a colleague while riding their bikes at around 10pm, an hour after the curfew kicked in.

The young men attacked immediately, and during the tussle, the officer was stabbed in the face with a sharp object, a police spokesman said. The youngsters then ran off on foot and despite a local alert, have not yet been traced.

Police are appealing for witnesses.