Fifteen foundation trusts finished 2011-12 in deficit and “at least four” are considered unviable in their current form by Monitor, HSJ has learned.

During a session at the NHS Confederation conference, Monitor policy director Toby Lambert said most of the 15 had small deficits that were within the boundaries of sustainable long term financial planning.

However, he added: “There are at least four [foundation trusts] which we have serious questions about ongoing long term financial viability.”

He told HSJ their problems were beyond that which could be solved by the organisation alone.

HSJ understands the four trusts are Mid Staffordshire, Heatherwood and Wexham Park, Peterborough and Stamford and the Royal National Hospital for Rheumatic Diseases in Bath.

Monitor recently wrote to the £20m-turnover Bath-based trust advising it that it did not consider it viable in its current form.

Mid Staffordshire’s finances spiralled out of control in the wake of the care scandal at the trust and its current long term plan only manages to reduce a £20m deficit to £11m by 2014-15. Locally it is widely expected to merge with University Hospital of North Staffordshire.

Commissioners and providers in Berkshire have already begun work on a plan to address long term financial problems at Heatherwood and Wexham Park which will involve finding a “partner” from the NHS or private sector.

Peterborough has been in significant breach of its terms of authorisation with Monitor since last October due to concerns about governance and financial viability. The trust has a deficit of around £56m largely due to an expensive private finance initiative deal.

Full details of the 15 trusts will be published by Monitor next month.