Police have released a CCTV image of a man they want to speak to in connection with a sexual assault on a 25-year-old woman from Wanstead.

The victim had boarded a train at Liverpool Street station on her own at around 1.40pm on May 11.

A man, who boarded at the same station, sat opposite her and during the journey, performed an indecent act while staring at her.

Investigating officer Det Con Jon Howlett said: “Feeling extremely uncomfortable, the victim got up, moved away from the man and stood in the vestibule area.

“As the train arrived into Stratford, the man stood up to leave and headed towards the victim, touching her inappropriately before he left the train.”

Witnesses who saw what happened are urged to come forward.

Mr Howlett added: “We are keen to speak to the man pictured in this very clear CCTV image, as we believe he has key information which could help our investigation.

“The victim was left understandably shaken by this attack.

“Assaults of this nature are extremely rare on the rail network, but, when they do occur, we will do all we can to find those responsible and bring them to justice.”

Anyone with information is asked to contact British Transport Police on 0800 40 50 40 quoting background reference B3/LNA of 13/06/2013 or call Crimestoppers anonymously on 0800 555 111.