NHS finance directors are already warning their plans to improve productivity in 2011-12 may not be met, less than a month into the financial year.

It comes as NHS chief executive Sir David Nicholson has cautioned against making “unrealistic” proposals and predictions about efficiency.

The King’s Fund said more than two thirds of a panel of 26 finance directors it has established “said they may not meet their [productivity] targets for 2011-12”. The group includes primary care, hospital and mental health trust directors from across England.

According to a King’s Fund analysis published yesterday the panel “called on the government to be more realistic about the challenges involved in finding the savings needed”.

The directors were also asked how they planned to improve productivity.

Twelve out of the 26 identified ward closures and reducing services among the main methods. Others included workforce changes, redesigning services to improve efficiency and reducing lengths of stay in hospital.

The King’s Fund said a number of directors were “sceptical” about making significant savings through “back office” efficiency. Only six cited it as a key area for productivity improvement.

The think tank published the findings yesterday as part of the first in a series of quarterly NHS monitoring reports.

It also looked at performance data, confirming the deterioration in waiting times shown in Department of Health statistics.

It said there has been a “steady increase in waiting times for hospital treatment since waiting times targets were relaxed in June 2010”.

The proportion of inpatients waiting more than 18 weeks in February was nearly 15 per cent – the highest proportion since April 2008.

There was also a “sharp increase” in patients waiting over four hours at accident and emergency between October and December, the latest period for which figures are available.

The King’s Fund said the rises “reflect seasonal factors, [but] they are not explained by this alone”.

King’s Fund chief economist John Appleby said: “This report… highlights significant concern among NHS finance directors – who are well placed to report on the stresses in the system – about the prospects for the year ahead.”

Private hospital provider Spire Healthcare also this week claimed a survey of 500 GPs which it commissioned showed they expected to increase private referrals during 2011 because of restrictions in the NHS and lengthening waiting times.