The financial crisis in the NHS is threatening to spiral out of control, shadow health secretary Andy Burnham warned tonight.

Responding to reports of a letter sent by the regulator, Monitor, to hospitals on the financial state of the NHS, leading to staffing cuts, the Labour leadership hopeful said: "This is a sign of a serious deterioration in NHS finances. It suggests that the financial crisis in the NHS is threatening to spiral out of control and hit standards of patient care.

"The suggestion that hospitals can ignore safe staffing guidance will alarm patients and the Government must decide if it will overrule this advice.

"Morale in the NHS is already at an all time low and doctors have lost confidence in the Health Secretary.

"It will raise further questions about how the Government can possibly fulfil commitments on a seven-day NHS without the money to back it up."

Health Service Journal reported that NHS providers have been told to take emergency measures to try to reduce the deficit predicted by the sector this year.

It said it had seen a letter sent this afternoon by Monitor chief executive David Bennett which restated that the current financial forecasts for 2015-16 are "simply unaffordable", and asked each foundation trust to revisit its plans.

The letter tells trusts to "ensure vacancies are filled only where essential", and ensure existing safe staffing guidance has been adopted in a "proportionate and appropriate way", HSJ said.

Trusts with large deficits have been given specific new end of year figures which Monitor believes they can achieve if they make the cost cuts outlined, it added.

The provider sector has forecast a total deficit of more than £2bn for 2015-16, HSJ said.