Officers say passengers are putting themselves at risk by using the cabs, and are urging people to report drivers operating illegally.

A number of bogus taxi driver incidents have been reported to Greater Manchester Police.

Only Hackney cabs are licensed to pick up passengers at the roadside, and private hire cars must be pre-booked.

A small number of bogus drivers deliberately set out to attack lone travellers

Supt Garry Shewan

Superintendent Garry Shewan, of Greater Manchester Police, said people take risks in the early hours of the morning when there are long queues for taxis.

He said: "By that time in the morning some people are so anxious to get home, they will literally get into any car that will stop for them.

"For women travelling alone, this has resulted in a number of sexual assaults, but it is equally dangerous for men who find themselves the victim of a violent assault or robbery.

"Bogus drivers sometimes just want to make money by ferrying people around without getting insurance or a licence, but a small number deliberately set out to attack lone travellers."

Police are urging anyone who knows someone operating an unlicensed taxi to call them, or Crimestoppers.