POLICE have arrested and charged a 26-year-old Helensburgh man for wilful and obscene exposure following an incident on a train at Gosford.

A rail worker at Gosford Railway Station noticed a passenger on an arriving train allegedly expose himself, before performing a sexual act about 6.30am on Monday July 2 .

Police were called and the man was arrested at the railway station.

He was taken to Gosford Police Station where he was charged with wilful and obscene exposure and for travelling on a train without a valid rail ticket. He was issued with a court attendance notice and is scheduled to appear at Wollongong Local Court on Tuesday July 31.