This man is wanted by police after performing a sex act on himself on a bus while staring at a fellow passenger.

The man, thought to be about 25-years-old, was on the 151 bus going from Rosehill towards Sutton town centre when the incident happened at 4.10pm on Thursday, August 22.

A 17-year-old girl got on the bus at the Rosehill roundabout and sat on the top deck.

After several stops more space opened up and she moved to a seat near the back of the bus but noticed the man follow her and sit on a seat across the aisle.

The girl, who can not be named for legal reasons, said: "I could feel someone staring at me and I was like 'what's going on?'.

"Then in the reflection in the window I could see him playing with himself.

"I didn't want to look at him so I pretended to be on the phone so I could take a picture just to double check it was what I thought.

"When I stood up to press the button and get off he sort of roared at me, like a strange moan.

"It was horrible."

Police are investigating the incident and are carrying out extra patrols along the route in the hope of catching the man.

He was dressed in a pink T-shirt, chequered shorts and white trainers.

If you recognise the man or have any other information about the incident, you can call police on 101 quoting reference number 4008129/13 or the charity Crimestoppers on 0800 555 111.