The woman, thought to be in her 30s, was assaulted at about 11pm outside Cruise nightclub, St John Street, after an altercation.

Cheshire Constabulary spokesman Dave Murray said: "At 11.07pm we had a report of a fight outside Cruise and an ambulance was called to a female in her 30s.

"It would appear she had been assaulted or was knocked over, whether deliberately or in the melee."

Det Cons Mike Beamish said: "A female was knocked unconscious, although it seemed she suffered minor injuries."

The incident came after a busy afternoon meeting at Chester Races.

Lesley Broadhurst , of the North West Ambulance NHS Trust, said an ambulance was called to the scene but was later cancelled by police.

It is thought that the woman didn't receive serious injuries and later regained consciousness.

A 23-year-old man from Ellesmere Port was arrested on suspicion of affray, and has been bailed to appear before Blacon Custody Suite on July 30.

A 20-year-old man from Chester was arrested on suspicion of assault, causing actual bodily harm, and bailed to appear back at the same custody suite on August 18.

A third man, a 20-year-old from Chester, was arrested on suspicion of affray and bailed to appear at the custody suite on August 18.

Anyone with information should call Cheshire Police on 0845 458 0000, or Crimestoppers anonymously on 0800 555 111.