Police have increased security in a Manchester hospital after three patients died when their medication was tampered with.

Staff at Stepping Hill Hospital in Stockport contacted the police after three terminally ill patients died, including an 84-year-old man, a 71-year-old man and a 44-year-old woman with multiple sclerosis.Eleven more patients were affected but not seriously harmed.

It has sparked fears that there is another “angel of death” who is a member of staff at the hospital. The police believe that insulin may have deliberately been added to saline drips.

Insulin was used in the 1990s by “angel of death” Beverley Allitt, in the murder of four children.

The deaths are being regarded as suspicious and patients are being monitored.

Assistant Chief Constable Terry Sweeney told the Daily Mail: “It is an extremely fast-paced investigation and we are working closely with the hospital and the coroner. Greater Manchester Police’s priority is to prevent any further harm to patients.

“As part of that we are advising the hospital in terms of increased security measures.

“We have recovered a number of ampoules of solution and are working closely with the hospital to try and get to the bottom of what has happened.”

He added that patients should not be worried: “There is no need for people to be unduly alarmed but I would ask anyone who might have information about what happened to get in touch.”

A major incident is working closely with staff there to find out the full circumstances.