A man woke up to find another man sexually assaulting him on a train.

British Transport Police (BTP) have released a CCTV image of a man in connection with the attack on board a train travelling to Colchester from Liverpool Street Station on March 4 this year.

A man woke up at around 7.30pm to find another man sexually assaulting him, BTP said.

The force has launched an investigation.

East London Advertiser: Police believe this man may have information that could aid their investigationPolice believe this man may have information that could aid their investigation (Image: BTP)Detectives would like to speak to the man pictured above, who they believe may have information that could help their investigation.

Anyone who recognises him has been asked to contact BTP by texting 61016 or calling 0800 40 50 40, quoting reference number 325 of March 5.

Alternatively, call Crimestoppers anonymously on 0800 555 111.