A woman who had fallen asleep on a bus headed for Corby woke up to find a man assaulting her.
Police are appealing for witnesses following the incident on a bus travelling into Kettering on Tuesday, January 10.
A police spokesman said: “A 19-year-old woman had fallen asleep on the top deck of the X4 Stagecoach bus from Milton Keynes to Corby.
“At around midday she woke to find a man sitting next to her and touching her inappropriately.
“She shouted at him causing other passengers to turn around and, feeling unsafe, got off the bus at Horsemarket, Kettering.
“The man remained on the bus.”
The offender is described as having short, dark hair, silvery teeth, clean shaven, about 6ft and wore a dark blue Puffa style jacket and navy jeans.
Officers would like to speak to anyone who was on the bus at the time of the incident, which police have just released details about.
Witnesses or anyone with information about it can contact police on 101 or Crimestoppers anonymously on 0800 111555.