The incidents, which happened within minutes of each other on Ringwood Avenue, Newbold, took place on Monday night.

A 50-year-old woman was getting out of her car at 10.30pm when a young white man approached and asked her for the time.

He made lewd comments as he groped her breast, indecently exposed himself and punched her on the side of the head.

Det Con Dave Portas, of Chesterfield CID, said: "She was very distressed by the incident. It has frightened her and she has no intention of being out on her own in the dark."

The attacker ran off towards Cranbourne Road when his victim started screaming.

Just 15 minutes earlier, a man of the same description had exposed himself to a 17-year-old girl who was walking along Ringwood Avenue with a female friend.

Det Con Portas said police believed the attacks were committed by the same offender.

But he added: "We want to know if other incidents were committed on that night. Some people can be reluctant to report these types of offences."

The attacker is described as a white male, of slim build, 5ft 10 to 6ft tall, aged between 17 and 20, with short dark hair. He was wearing a dark top with the hood pulled up.

Anyone with information about the incidents is urged to contact Derbyshire Police on 0845 123 3333 or Crimestoppers on 0800 555 111.

* An 18-year-old man was arrested on suspicion of indecent exposure and indecent assault on Monday night. He was released on police bail on Tuesday pending further enquiries.