A fifth Briton has died after suspected insulin poisoning at a hospital in northwest England.

Linda McDonagh is one of 21 patients who police believe were affected by contaminated saline administered on acute care wards at Stepping Hill Hospital, in the town of Stockport, between June and July 2011.

The 60-year-old, who lived locally, died on Jan. 14. Like several other patients, she had suffered hypoglycemic episodes after the saline drips were contaminated, the Manchester Evening News reported.

A spokesman for Greater Manchester Police said, "The woman, who was one of a number of patients who police believe suffered hypoglycemic episodes between June and July 2011 after being administered contaminated products at Stepping Hill Hospital, died in the early hours of Saturday, January 14.The coroner has been made aware and further tests are ongoing."

Tracey Arden, 44, Arnold Lancaster, 71, and Derek Weaver, 83, died after experiencing similar hypoglycemic episodes to McDonagh.

Police are investigating also whether the death of 82-year-old William Dickson, who was treated at the hospital during the summer, is related to the poisonings.

Earlier this month, a 46-year-old male nurse, Victorino Chua, was held on suspicion of murder in connection with the investigation. He was released on police bail until April pending further inquiries.

Chua was initially arrested on suspicion of tampering with medical records and was then re-arrested on suspicion of three counts of murder and 18 counts of causing grievous bodily harm.

Chua was one of 650 people already questioned by detectives involved in the case. Nurse Rebecca Leighton, 27, was arrested on suspicion of murder in July but was released without charge.