The report, entitled Count Me In and produced by the Healthcare Commission and the Mental Health Act Commission, details the results of a March ethnicity census of acute psychiatric inpatient wards in England and Wales.

The census covered almost 34,000 mental health inpatients using services provided by all 102 eligible NHS trusts and 110 independent providers in England and Wales.

Ms Winterton described Count Me In as “a vital building block towards our aim of eliminating inequalities in mental health services.”

In January the government launched a five-year race equality action plan in a bid to eradicate racism in mental health services.

The plan included a pledge to improve race equality training for mental health staff. Seventeen strategic health authorities have also been asked by the government to set up non-discriminatory mental health projects.

Ms Winterton said: “I know that many services around the country are improving the care they provide for ethnic minority communities and I am confident that we have started to build the sort of service that can make the inequalities that the census confirms a thing of the past."

Campaigners have concerns, however, that NHS trusts do not have the funds to deliver long-lasting change.

Angela Greatley, chief executive of the Sainsbury Centre for Mental Health, said mental health services “face an uphill task to deliver race equality".

She said: "The government’s delivering race equality action plan is a bold and ambitious attempt to put this injustice right. But it will only work if there is concerted action, backed up with new investment, to help those trusts with the biggest problems.

She added that government plans for a new mental health law – outlined in a draft mental health bill – should contain a race equality assessment.

"It is vital that there are clear lines of accountability for achieving change over time," she said.

"The inequalities laid bare today must be a cue for action and not become accepted as routine fact.”