Man charged over Sydney train knife threat

A man is in custody after he allegedly threatened a teen boy on a train with a knife.

The 17-year-old got on the citybound train at Killara in Sydney's North Shore around 9.15am on Sunday morning.

A short time later, a man entered the carriage and sat nearby. He then approached the boy and threatened with him a knife, police will say in court.

The boy got off the train at Milsons Point and contacted police.

The 37-year-old Terrey Hills man was arrested around 9.30am after a short foot chase.

Police found a knife hidden in his pants and a flick knife and scissors in his pockets.

The man has been charged and will appear at Central Local Court on Monday.