A driver pulled up alongside a teenage girl and touched her bottom.
The incident is one of three in which a driver of a blue hatchback car has been reported approaching girls in Brighton.
The first was on August 5 at around 7pm when a 14-year-old from Estonia was approached.
The teenager, who has been staying with a family in Patcham whilst studying English in Brighton, was walking along a road believed to be Ladies Mile Road, Patcham. She refused to get in the car and he drove off.
The following day two girls were walking along Carden Avenue at 3.40pm when a blue car stopped and the driver stared at them before letting them cross the road.
They went into Asda in Hollingbury and saw the same car driving around the car park.
Around 7pm that day a 16-year-old girl was out jogging in Tongdean Lane when a blue car drove past her and the driver leaned out and touched her bottom.
Detective constable Leon Howe said: "All the girls did the right thing by reporting this suspicious behaviour to police.
“The man on Ladies Mile Road and Tongdean Lane is described as being white, in his 20s with short blond hair.
“The Carden Avenue man is described as having short brown hair and glasses. The car is always described as a small blue car.
"We are asking if anyone has seen this car acting suspiciously or anyone has any information about these incidents to contact police on firstname.lastname@example.org or call 101 quoting serial 1484 of 6/8."