The mother of a 14-year-old patient who killed herself at a Priory hospital has called the company “morally bankrupt” after it emerged that the firm was fined less than two days’ profit over the death of her daughter.

Amy El-Keria was being treated at the group’s Ticehurst House psychiatric hospital in East Sussex when she was found dead in her room in November 2012.

Following a campaign by her family, Priory Healthcare was last month fined £300,000 over the death, an amount decided by a judge who took into account the fact that the firm pleaded guilty to criminal charges and said its 2017 turnover was £133m with an operating profit of £2m.

However, campaigners now argue that the figure is only a fraction of what its parent company was making, with the Priory Group’s overall accounts for 2017 revealing an operating profit of £62m – around £170,000 a day. The total revenue for the group, Britain’s largest mental health and adult care provider, was £797m, of which around 90% (£720m) came from the public purse, the NHS and social services.

It has also emerged that the Priory Group gave its boss at the time of El-Keria’s death a £458,000 payment when he left the firm that year, a sum more than half again what the company was fined over the tragedy.

Priory Group accounts reveal the highest paid director in 2012 received £829,000, of which £458,000 is described as “compensation for loss of office”. A spokesman for the firm said the payment could not be described as a “golden goodbye” but was made “strictly in accordance with relevant contractual provisions”.

The Priory are a morally bankrupt company. They take large sums of public money, placing profit over safety Tania El-Keria

An inquest in 2016 found “gross failings” of the group had contributed to El-Keria’s death at a specialist children’s unit at the hospital. Staff shortages, a failure to assess ligature points and inadequate monitoring were cited by the coroner as contributors to her suicide. Amy was taken to hospital and died the next day.

Amy’s mother, Tania El-Keria, said: “Our Amy died in what we now know to be a criminally unsafe hospital being run by the Priory. To me the Priory are a morally bankrupt company. They continue to take large sums of public money, allowing our children to suffer by placing profit over safety. This cannot be allowed to continue, and I will not stop fighting until this stops.”

Deborah Coles, director of charity Inquest, said: “The marketisation of our mental health system enables companies to put profit over the safety of children in their care. The lack of any independent system of investigation allows the Priory to investigate their own actions. This meant it took six and a half years for their criminally unsafe practises to be exposed following Amy’s death. This dangerous and harmful situation continues to this day.”

The profits and finances of the Priory Group, revealed following an investigation by Corporate Watch, will intensify scrutiny on why a private company guilty of criminally unsafe practices is allowed to care for some of society’s most vulnerable citizens.

“The investigation by Corporate Watch raises serious questions about the Priory’s profits, a concerning level of which are gained from running NHS-funded services,” added Coles.

Scrutiny of accounts also reveals that in the year Amy El-Keria died the Priory received a £1m tax rebate from the government, which the firm said “related to an overpayment of tax from an accounting period prior” to its acquisition by a global private equity firm in 2011.

At Lewes Crown Court last month the Priory Group pleaded guilty to health and safety offences, with the judge, Mr Justice Dingemans, imposing the £300,000 fine after also taking into account the company’s “good” health and safety record and steps made to improve the service.

Sentencing the London-based private company Priory Healthcare, a subsidiary of the Priory Group which runs Ticehurst hospital, the judge said the penalty could “never reflect the loss suffered by Amy’s family”.

Campaigners at Inquest have consistently highlighted the failures of oversight and scrutiny concerning the deaths of children in mental health facilities, claiming there is an absence of publicly available information about the number and circumstances of deaths of children who have died while receiving in-patient mental health care from private providers.

A parliamentary answer revealed that during the financial year 2017-18, the Department of Health reported that 44% of child and adolescent mental health services expenditure was on services by the “independent sector”, of which the Priory is a significant recipient.

A spokesman for Priory Healthcare said: “We strongly refute any allegation that we put profit before safety. We have a robust, board-led safety culture and once financing costs are met, surplus cash is invested in our buildings and services with the absolute priority being patient safety. Across our 84 CQC [Care Quality Commission]-registered healthcare sites, 87% of our sites are ‘good’ or ‘outstanding’, compared to 78% in the NHS or other independent providers.”