Almost two fifths of independent sector mental health units do not comply with rules set out in the Mental Health Act, according to Care Quality Commission data.
A snapshot analysis of CQC records at 28 August found that while 39 per cent of facilities run by independent sector providers failed to comply with the act, the same was true of only 15 per cent of those run by NHS mental health trusts.
The data is based on inspections of 294 NHS sites and 188 independent sector locations since the CQC was formed in 2009.
The regulator cautioned against drawing conclusions based on the figures, which it said represented only a snapshot of a single point in time.
The disparity in performance emerged at a talk by CQC policy lead for mental health Heather Hurford, at the Camden and Islington Foundation Trust nursing forum event in London last week.
Ms Hurford also revealed the top five concerns about compliance with the Mental Health Act - across NHS and private providers - were patient participation and care planning; ward environment; medication issues; leave; and rights of detained patients.
She told the event: “Huge numbers of people are receiving very good quality care but there are huge problems in some areas and on some wards in parts of the country.”
Despite the Mental Health Act being law since 1983, Ms Hurford said CQC inspectors still found too many breaches.
One example of bad practice she cited was a ward of 16 patients with no ensuite facilities and in which three out of the four toilets were out of order for more than a week. In another case Ms Hurford said leave was taken away from patients as a punishment.
She said if staff were not well supported there was a risk they could begin “behaving in deviant ways”.
“Institutionalised behaviour can easily creep in and become normal far too quickly,” she warned.
CQC inspectors found physical restraint had been used as a standard first response to disturbed behaviour. Male staff had restrained female patients, patients suffered injuries and medical reviews were not taking place following restraint.
She also pointed to patients being segregated without relevant safeguards in place, with food and drink given in ways that compromised their dignity.