About 6.40pm, a 34-year-old man was travelling on a train between Thirroul and Hurstville with three friends, when a man approached the group, allegedly making threats.

A short time later, the man reapproached the group and allegedly assaulted the 34-year-old, causing a cut to his lip.

The group restrained the man and on arrival at Hurstville station, police were called and the man was arrested.

The 27-year-old Penshurst man has been charged with assault occasioning actual bodily harm and granted conditional bail.

He will appear at Kogarah Local Court on January 7, 2014.