Grenades left at Gold Coast police station

Four grenades have been left at a Gold Coast police station by a man who claimed they were lost property.

A man in his 60s dropped off a box containing the grenades inside Nerang Police Station around 9am on Wednesday, before riding away on a bike.

Several minutes later a staff member checked the box and saw the grenades. The box was immediately taken to the car park.

An explosives expert identified them as three flash-bangs and one smoke grenade, which have minimal risk due to their condition.

Police do not believe it was a threat but are searching for the man who is 175cm tall, has short grey hair and a medium build.