Families of people treated on the Stroke Unit at Blackpool Victoria Hospital are being contacted by detectives, after a nurse there was arrested on suspicion of poisoning patients.
The unnamed medic was reported to police by colleagues concerned about her behaviour, it was understood.
The nurse was arrested on November 9 – the day after concerns were raised – on suspicion of “administering any poison or noxious thing with the intent to injure, and ill treatment or wilful neglect”, police said.
She was bailed until Thursday, December 6, as a “complicated” investigation at the Whinney Heys Road hospital continues.
Vic boss Wendy Swift (inset) said “all allegations of this type” are taken “extremely seriously”, and said she wanted to “reassure all our patients that all necessary actions are being taken”.
She added: “The hospital remains a safe and caring environment for patients and the provision of services will continue as usual.”
When asked how patients, if any, are known to have been hurtand how many families are being contacted, a hospital spokesman said there would be no further statement.
Detectives were yesterday still in the process of identifying any victims, with Lancashire Police saying it was too early to say how many patients had come to harm.
“We have started to contact the family of those who might be affected,” a statement read.
“They are being supported by specially-trained officers.”
The force did not say how many families had been contacted.
Det Ch Insp Jill Johnston added: “The inquiry is complicated and we have a team of specialist detectives working on this case who are also offering support to those families who have had loved ones identified as potentially being involved.”
Anyone with information can call police on 101, quoting log reference 0553 of November 14, or report it online to the major incident public reporting website at mipp.police.uk