Workers have been suspended from a hospital operated by a company at the centre of a BBC investigation into abuse.
The health watchdog has raised "a number of concerns" about two hospitals operated by Castlebeck.
The Care Quality Commission (CQC) has visited Arden Vale in the West Midlands and Croxton Lodge in Leicestershire.
Some staff were suspended following misconduct allegations at Arden Vale and police are investigating.
Panorama filmed staff allegedly abusing patients at the company's Winterbourne View home in Bristol.
A spokeswoman for Castlebeck said: "We can confirm that a number of staff members have been suspended following allegations of misconduct at Arden Vale."
She added they were working with and had notified all relevant authorities but were unable to comment further as enquiries are ongoing.
Arden Vale, in Meriden, is a 25-bedroom independent hospital.
A statement on its website says it specialises in assessing, treating and supporting people with a learning disability and severe challenging behaviour and/or associated mental illness including those liable to be detained under The Mental Health Act.
Croxton Lodge, in Melton Mowbray, is described in a similar way and has spaces for 30 patients.
A spokesman for the CQC said it has recently been reviewing all services provided across England by Castlebeck.
He said: "As part of that work our inspectors have been reviewing the standard of care at Arden Vale and Croxton Lodge."
He said they made unannounced visits to Arden Vale on 3, 13 and 14 June 2011.
"We have a number of concerns that we have raised with the provider, who we are in regular contact with," he said.
He added: "We are closely monitoring the care and safety of people using services at Arden Vale, along with the local safeguarding authority and the organisations that are paying for the care of people at Arden Vale."
The spokesman said CQC inspectors visited Croxton Lodge on 6 and 11 June 2011.
"As a result of these unannounced inspections we have raised some concerns with the provider," he said.
"We continue to monitor Croxton Lodge and our full report will be published at the end of July; until then we cannot, for legal reasons, comment further."
Following the BBC Panorama programme earlier this year, Castlebeck's Winterbourne View was closed.
Earlier this month the BBC learnt four members of staff were suspended at Rose Villa, a nine-bed rehabilitation centre in the Brislington area of Bristol, also run by Castlebeck.