A hospital trust that has been losing £1 million a week is to be put in special measures as Health Secretary Andrew Lansley seeks to turn around its dire financial situation.

South London Healthcare NHS Trust will be the first in the country to be put under the control of a special administrator tasked with putting it on a viable footing.

The trust, which runs three hospitals, has been criticised over standards of care and has run up deficits of more than £150 million over the past three years and it is thought to be on track to lose between £30 and £75 million a year for the next five years.

Its chief executive was informed on Monday night that the trust is likely to be put into the "unsustainable providers regime" which was introduced by the last Labour government but never before used.

The trust runs Queen Mary's in Sidcup, the Queen Elizabeth in Woolwich and the Princess Royal University Hospital in Bromley. It released a statement this evening reassuring patients that services would continue as normal.

Mr Lansley acknowledged the move would be "unsettling for staff" but said the measures were necessary to ensure hospital services in south east London had "a sustainable future".

The trust pointed out that it had one of the lowest mortality rates in England and infection rates three times lower than the national average.

In a statement, it said: "We have entered into discussions with the Department of Health and NHS London on the best future for the Trust and our priority, and that of others involved, is to make sure that our longstanding and well-known financial issues are resolved.

"Our staff have worked hard for patients and in spite of significant financial issues, we are extremely proud that we now have among the lowest mortality and infection rates in the country.

"We expect these discussions to come to a conclusion in the second week in July when a decision will be taken by the Secretary of State.

Rob Macey of the GMB union said, "The decision to call in administrators is nothing short of disgraceful.

"If the Trust is dissolved there will be devastating consequences for both patients and staff. This Trust has never had the opportunity to succeed due to the crippling historical debt inherited from a private sector finance deal.

"It cannot be right that we have a Government that is prepared to bail out the banks but not our NHS. GMB is therefore calling on the Government to bail out this Trust to give it a chance to succeed."