Police are investigating after a man was photographed allegedly masturbating on a Dartford train over the weekend.

The incident is said to have happened around 7:45am on Saturday morning (May 16).

A photo of a man appearing to masturbate was posted on Twitter by @HannahTweedy.

A British Transport Police (BTP) spokesman said: "We are aware of an image posted on social media that appears to show a man indecently exposing himself onboard a train.

"Officers are investigating. It is not currently clear when or where the photo was taken.

"We would appeal for the person who took the photo to contact us on 0800 40 50 40, or text 61016, quoting reference 505 of 18/05/2015."

UPDATE: A 44-year-old man from Gravesend was today (May 20) arrested in connection with this incident.