Patients at some of London's leading hospitals are still being forced to sleep in mixed sex wards, it emerged today.

Barts and the London and Imperial College Healthcare trust are failing to provide enough single-sex wards, a major patient survey found. Patients rated the trusts among the worst in the country for their mixed-sex wards.

The Government has announced that hospitals will be fined from next year if they continue to treat patients in mixed-sex wards.

Health secretary Alan Johnson has pledged £100 million to help hospitals create single-sex wards, and said they will not be paid for the care of patients they treat in mixed-sex facilities.

The Government has been plagued by the pledge for 12 years — Labour first announced it would abolish the wards in its 1997 election manifesto.

A survey by health and social care watchdog the Care Quality Commission shows patients rated Barts and the London and Imperial College Healthcare were below average on the lack of single-sex wards. The two trusts include Charing Cross, Hammersmith and St Mary's hospitals.

The poll, taken last summer, showed 31 per cent of patients at Barts and the London and 39 per cent at Imperial had to sleep near a person of the opposite sex. At the Royal Marsden, rated as one of the best hospitals in the country, only five per cent were in mixed-sex wards.

A spokesman for Barts and the London said the trust has reduced mixed-sex wards by 82 per cent between November 2007 and November 2008. He added: “We reduced the number of occasions when men have been either next to or opposite female patients from 646 instances to 183 per month.”

“The brand-new buildings currently under construction at Barts and The Royal London hospitals will be fully compliant with the single sex standard when they open in 2010 and 2012 respectively.”

A spokeswoman for Imperial College Healthcare said the trust is spending £9 million to eliminate mixed sex accommodation by March next year.

She added: “Before this work is complete, due to clinical need, patients may need to spend limited time in mixed sex accommodation.”

The Care Quality Commission's chief executive Cynthia Bower said: “We want to ensure the voice of patients rings loud and clear in every NHS trust. We make no apologies for demanding high standards.”