Confusion surrounding the government’s public health budget is “undermining confidence” in its ability to deliver a competent strategy in this area, the Commons health committee has warned.

Ministers have proved “unable to provide any detailed explanation” on how they arrived at the £4bn estimate for current public health spending quoted in last November’s white paper, the MPs say in a report examining the government’s public health reforms.

The committee said academics had told them the £4bn “appeared to derive specifically” from an estimate of health prevention expenditure from 2006-07, which did not include the other two public health domains – health promotion and healthcare public health.

Department of Health witnesses “were not able to enlighten us greatly” on the issue, while public health minister Anne Milton “confessed that she did not entirely understand” the distinction between spending on frontline public health and support services, the MPs said.

Committee chair Stephen Dorrell told HSJ it had been “ill advised” of the DH to “put a number into the public domain” without an accurate definition of what it represented.

The report notes the DH is currently compiling a historic baseline for future public health allocations, using primary care trust expenditure returns for 2009-10. It urges the DH to “show in detail exactly” how it has calculated the baseline when it is announced later this year.

In a wide ranging report, the committee also criticises DH proposals for a “health premium” to reward higher achieving councils with additional funding, which it says risk “widening health inequalities”.

It also says plans to ringfence public health allocations “risk encouraging” councils to only view spending from these budgets as public health, running counter to the aim of integrating services. There is also a risk of councils “gaming” by “redesignating” services already provided from other budgets – the example given was pothole filling. As a result, the committee says the ringfence should operate for no more than three years.

Mr Dorrell said he was “extremely sceptical” about ring-fencing’s overall effectiveness but thought it had potential to “influence behaviour in the short term”.

Responding to concerns about the future status of directors of public health in councils, the report said it should be a statutory requirement for DPHs to be appointed at chief officer level. It said a DPH should be on the board of every clinical commissioning group and the NHS Commissioning Board itself.

Further recommendations made by the committee included ensuring Public Health England was “visibly and operationally” independent of the DH and that the health secretary had a statutory duty to reduce public health inequalities.

It also calls on the government to review its opposition to the mandatory regulation of public health specialists – as lobbied for by the Faculty of Public Health – and recommends that uncertainty around staffing issues during the transition period be resolved “as quickly as possible” to halt the low morale that is “causing people with valuable skills to leave”.