A man has been charged after allegedly indecently assaulting a 13-year-old boy on a train yesterday.

About 4.40pm (Saturday 28 March 2015), police will allege a 48-year-old man sat next to the boy and his two friends on a Newcastle bound train.

The man allegedly offered the boy alcohol before indecently assaulting the boy.

The boy and his friends stood up and walked away from the man, who started to follow the group before being stopped by another passenger.

Police were notified of the incident and met the train at Woy Woy Railway Station and arrested the man.

He was taken to Gosford Police Station and charged with indecent assault upon person under 16, common assault and stalk / intimidation.

He was granted strict bail conditions to appear before Gosford Local Court on Tuesday 31 March 2015.