By Ian Youngs BBC News Online

A £20,000 reward has been offered for the medallion's return

Mr Morrison, known for his 1996 hit Return of the Mack, spent a night in cells after the incident at Leicester's After Dark nightclub on Saturday night.

But he said he was the victim and has complained of wrongful arrest, unlawful imprisonment and police assault.

A police spokesman said a 32-year-old man was "released on police bail pending further enquiries".

He said the man had been "arrested on suspicion of assault and affray".

A £20,000 reward for the return of the pendant has been offered by the singer's record label.

Mr Morrison, 32, told BBC News Online a man who appeared to be a fan approached him in the club and "sucker-punched" him.

The police arrested me and threw me down to the ground Mark Morrison

"As I put my hand out, he reached out for my chain, ripped it off my neck and made an exit from the club," he said.

"As I gave pursuit, immediately eight security men from the club grabbed hold of me and ejected me from the nightclub.

"As I was ejected, the police arrested me and threw me down to the ground and I sustained injuries to my lip, my eye and the back of my head. I was assaulted in the street."

He also said Leicester Royal Infirmary refused to treat him because of a "confrontation" between him and the police.

At 1730 BST (1630 GMT) on Monday, he said his injuries amounted to "swelling on my head, a little fat lip, a little scratch on my eye". "I'll be back to work in the morning," he said.

The singer said he had told lawyers to make a complaint to the Chief Constable of Leicestershire Constabulary.

I don't know why Kevin Campbell wants to put a reward out - that's unnecessary right now Mark Morrison

Police said they were investigating assault against Mr Morrison and the theft of the medallion.

"We are investigating an allegation of assault and robbery on a 32-year-old man," a further statement said.

"The incident took place in a nightclub in Church Gate in Leicester at about 0030 BST on Sunday 1 August. Enquiries are continuing."

Mr Morrison hit number one in the UK in March 1996 with Return of the Mack, which he followed up with four UK top 10 singles.

His latest single, Just A Man, was released on Monday.

Nature has a way of trying to drag you back down and get involved in the wrong sort of publicity Kevin Campbell 2 Wikid Records

The pendant was made to mark his record real with 2 Wikid Records, the label set up by Everton football striker Kevin Campbell.

But Mr Morrison refuted the reward, saying: "I can buy 10 more chains - I don't know why Kevin Campbell wants to put a reward out.

"That's unnecessary right now. Kevin Campbell needs to pick up the phone and come and speak to me."

Campbell said the incident was a "catastrophe" for his new single.

"On his part it's frustration - he wants to get on and do things the right way," he told BBC News Online.