Drug dealers delivered crack cocaine to vulnerable patients at a mental health hospital, the BBC has been told.
It is one of the claims made by a number of former patients at units run by the Tees, Esk and Wear Valleys NHS Foundation Trust, which have seen five deaths in less than two years.
The trust has been criticised over its services at three hospitals, including West Lane in Middlesbrough, where three teenage girls died.
The trust said reviews were under way.
One girl admitted to West Park Hospital in Darlington last year told BBC Inside Out: “Definitely the most alarming [thing] was the presence of crack cocaine on the ward.
“There were two ways [to get it]. Either people left and brought it back in with them, or you could ring a dealer and they would come on to the ward and deliver them for you.”
She also said staff were “tipped off” ahead of a Care Quality Commission (CQC) inspection.
“They were told in advance what would be happening,” she said.
“Charts that weren’t present before were put up with dates and ticks placed on them, and patients were advised by staff to hide contraband on the day of inspection.”
The CQC said the trust was not told when inspections would take place, but did know which services would be looked at.
The former patient also said she saw an agency worker acting inappropriately by massaging a patient’s feet and telling another she was “beautiful”.
“It was really quite disturbing and made me feel uncomfortable,” she said.
One girl, who was admitted to West Lane in Middlesbrough with an eating disorder in 2015, said she was still “haunted every day” by the memories of her time there.
“It was a horror story from day one,” she said.
She said patients had access to scissors and wires, and liquids such as nail polish remover or paint which some drank.
“Even after things like that happened they wouldn’t then be taken away,” she said.
“We would just be told ‘well, if you want to do it that’s up to you’.”
She also said members of staff would ask patients with eating disorders such as anorexia and bulimia for “diet tips”.
West Lane closed in August after a damning inspection by the CQC.
At Roseberry Park in Middlesbrough, patients told the BBC some staff felt they had a licence to “treat you terribly”.
“They say [you have a] personality disorder, that means they can do whatever they want,” one said.
Having seen the BBC’s evidence, Marjorie Wallace, CEO of mental health charity Sane, said she was “absolutely appalled” and “the picture of neglect, even amounting to cruelty, means it’s more redolent of the dark ages of the old asylums”.
“The trust should be put into special measures immediately and those involved in all those incidents should be held to account,” Ms Wallace said.
The trust said it was “deeply sorry” that at West Lane it “didn’t provide safe, high quality care”.
A spokesman said the BBC provided too little information for it to respond to the specific allegations made by patients, and a number of reviews and investigations were under way so it would be “inappropriate to discuss or comment” further.
But he urged any patients with concerns to tell the trust, adding: “We take all such views extremely seriously and use what they tell us to improve their care and the care of others.”
You can see more on this story on BBC Inside Out North East & Cumbria on BBC One at 19:30 GMT on Monday 23 March and afterwards on the BBC iPlayer.