Staff at a hospital where a patient died after drinking cleaning fluid speak such poor English that they need translators, an inquest heard.

A coroner expressed concern that failing to understand the language could have contributed to a situation which meant Flash was put in a water jug and drunk by Joan Blaber, 85.

The tragedy took place at Royal Sussex County Hospital in Brighton last September, and led to Mrs Blaber’s death. The hospital admitted it still does not know how the deadly liquid ended up in a water jug.

Police have interviewed 100 medical and cleaning staff to ascertain if a crime has been committed. Officers know who gave her the jug, but said last week they had no plans to charge anyone. A jury will determine what happened at a full inquest later in the year – but further details emerged during a preliminary hearing at Brighton Coroner’s court.

A coroner expressed concern that failing to understand the language could have contributed to a situation which meant Flash was put in a water jug and drunk by Joan Blaber, 85

Coroner Veronica Hamilton-Deeley said it was ‘very worrying’ that the matter remained unexplained eight months on, and that it still had to be asked if it could happen again.

She said a post-mortem examination revealed the cleaning fluid was a ‘direct cause’ of death, and went on: ‘There is no evidence someone did this deliberately but it lurks on the back of one’s mind because this was such an extraordinary thing to have happened.’

The coroner said she was ‘caused anxiety’ by the fact that some of the staff members involved had to be interviewed by police through interpreters.

She asked: ‘How do you train staff, who may have been able to manage basic communication, in the rather more intricate matters you need to understand when you are handling and dealing with substances which ... are potentially extremely hazardous?’

Detective Inspector Julie Wakeford, of Sussex Police, confirmed a nurse involved in the incident was interviewed in English with the assistance of a Spanish interpreter.

She added that there were no plans for any criminal charges to be brought against any individuals, and ‘insufficient evidence’ to bring a corporate manslaughter charge against the hospital trust.

Police have interviewed 100 medical and cleaning staff to ascertain if a crime has been committed. They know who gave her the jug, but have said they had no plans to charge anyone

She said: ‘We believe we have identified the member of staff who placed the water jug at Mrs Blaber’s bedside.

‘We know later when she was given her medication it contained Flash cleaning fluid. We don’t know how it came to be in there.

‘After interviewing 90 to 100 people we are still not any closer to finding the answer to that.’

Lawyer Andrew Perfect, representing Brighton and Sussex University Hospitals NHS Trust, said: ‘We have no idea how it came to pass that cleaning fluid was in a jug that was designed only to hold water.’

In response to fears that other patients could be killed in the same way, Mr Perfect said the cleaning fluid had been removed from the wards and was no longer used by the trust.

The Care Quality Commission has carried out its own investigation which is due to be published this week.