Four more healthcare professionals have been arrested over the suspected poisoning of patients at a hospital stroke unit.
Two women and one man were previously arrested after Lancashire Police was informed in November by bosses at Blackpool Victoria Hospital about concerns over care provided to some patients.
On Wednesday, police said three women and one man were in custody after they were held on suspicion of administering any poison or noxious thing with the intent to injure and ill treatment or wilful neglect.
The unit is also at the centre of a separate murder investigation involving Blackpool pensioner Valerie Kneale, 75, who died there on November 16.
A post-mortem examination revealed an “unexplained injury”.
Officers are working closely with Blackpool Teaching Hospitals NHS Foundation Trust and HM Coroner for Blackpool and Fylde as part of the investigation.
More post-mortem examinations are taking place as part of the inquiries, police said.
The three healthcare professionals arrested in November and December were later released under investigation pending further inquiries.
All seven arrested individuals – understood to be six nurses and one healthcare assistant – are currently suspended from work.
Detective Chief Inspector Jill Johnston, of Lancashire Police, said: “Our investigation into allegations of mistreatment and neglect of patients at Blackpool Victoria Hospital is very much ongoing.
“I understand further arrests could be concerning but I would like to reassure people we have a dedicated team of detectives working on this investigation.
“Our priority and the priority of Blackpool Teaching Hospitals NHS Foundation Trust is to ensure the safety of patients.
“Given the number of arrests and the nature of the allegations, it remains a complex and sensitive inquiry.
“No timescales have been set and I would ask people to remain patient while we continue to conduct our inquiries.
“A number of post-mortem examinations have taken place in connection with our investigation and we are supporting those families who have had loved ones identified as potentially being involved. They are being kept fully updated and supported throughout the process by specially trained officers.
“We are working closely with the trust as well as HM Coroner for Blackpool and Fylde as part of the investigation.”
Anyone with information can contact police on 101, quoting log reference 0553 of November 14.
No arrests have been made in the murder inquiry.
In February, Mrs Kneale’s family said: “We, as a family, are completely and utterly devastated and heartbroken to have lost Val in these circumstances.
“She was the most precious wife, mother and grandmother, our constant friend and problem solver who we will miss dearly.
“We kindly ask our privacy is respected while we continue to come to terms with our loss.”