A police investigation has been launched after allegations were made about the treatment of a man with mental health problems, who subsequently died at the Norfolk and Norwich University Hospital.

And Norfolk and Suffolk NHS Foundation Trust has confirmed that four members of staff have been suspended while the investigation takes place.

The man, in his late 40s, had been receiving treatment at Hellesdon Hospital in Norwich when he had what police described as a 'medical emergency' on Tuesday, October 1.

Norfolk police said there had been an 'allegation' around the care he received before he was taken to the Norfolk and Norwich University Hospital, where he died on Friday, October 4.

A post-mortem examination was carried out, but has not established the cause of death, so further tests will now be carried out.

The death is being treated as unexplained and an investigation, led by the joint Norfolk and Suffolk Major Investigation Team, is currently underway.

Senior investigating officer, Detective Chief Inspector Tracey Little, said: 'We are investigating an allegation around the care the patient received prior to and during the medical emergency.

'A Home Office post-mortem examination has been carried out but proved inconclusive and further tests will now be carried out.'

The man's next of kin have been informed and are being supported by police.

Roz Brooks, director of nursing, quality and patient safety at the Norfolk and Suffolk NHS Foundation Trust, which runs Hellesdon Hospital, said the trust was also conducting its own internal investigation and four workers had been suspended.

She said: 'As well as conducting our internal investigation, we are assisting Norfolk police with their inquiries following a serious incident at Hellesdon Hospital in Norwich on October 1.

'Patient safety and protecting the vulnerable is the trust's main priority and, as such, we contacted police as soon as concerns were identified. 'We can confirm that four members of staff have been suspended pending further investigation.

'We are in contact with the family and have expressed our sincere condolences. We will not be releasing any further details at this time in line with their wishes.'

Police were quick to stress that the case was not linked to the ongoing enquiries at the James Paget University Hospital in Gorleston.

A middle-aged hospital worker there has been arrested on suspicion of murder after a patient died after an alleged drugs overdose.

James May, 76, died at the hospital on September 20 after collapsing with a suspected heart attack and a post mortem examination determined the cause of death as heart failure.

But the hospital reported an allegation of medical malpractice in connection with his death to police on Monday, September 30.

The death is being treated as suspicious and an investigation, led by the joint Norfolk and Suffolk Major Investigation Team, is currently underway.

Det Insp Little said, of the Hellesdon Hospital investigation: 'We can confirm there are no links to any other enquiries currently being undertaken by the Major Investigation Team.'