The care services minister has warned NHS England he may intervene to ask it to reconsider funding decisions if they undermine the government’s commitment to parity of esteem for mental health.

Speaking exclusively to HSJ, Norman Lamb attacked the “flawed and unacceptable” decision by NHS England and Monitor to cut the tariff price for mental health and community trusts’ services by a fifth more than the reduction proposed for acute providers.

Mr Lamb said the Department of Health would scrutinise trusts’ draft budgets in the coming months and would act if evidence emerged that mental health’s finances were suffering “unduly”.

HSJ’s last week revealed NHS England and Monitor had justified the tariff differential on the grounds that the costs of implementing the Francis report’s recommendations applied only to the acute sector, prompting claims there was an “institutional bias” against mental health.

The government’s refreshed mandate for NHS England, unveiled in November, set out a commitment to “taking forward actions to deliver a service that values mental and physical health equally” - a commitment reiterated in a speech on Monday by deputy prime minister Nick Clegg.

HSJ understands ministers had been unaware of the differential tariff until last weekend, prompting a series of conversations with officials.

Mr Lamb told HSJ he was “appalled” by NHS England and Monitor’s actions and said it was “essential” the system was “held to account” for delivering parity of esteem.

“I think it is a flawed and unacceptable decision,” he said. “The government response to Francis was very clear this required a system wide response and it applied equally to mental health.

“Safe staffing is as important in mental health as anywhere else so the decision can’t be justified.”

Describing how the DH would take action, Mr Lamb said: “The draft budgets from non-FT and FT mental health trusts will be coming in and we will scrutinise them. If there is any evidence that mental health is suffering unduly, financially, then we will have to go back to NHS England to say the mandate is quite clear and we need to deliver on this.

“I will be absolutely clear on this. The mandate can’t be rhetoric. It has to be taken deadly seriously.”

The minister’s comments constitute the clearest example so far of a minister threatening to intervene under the terms of the 2012 Health Act which gave NHS England operational independence from the DH.

Mr Lamb also urged clinical commissioning groups to look at mental health “in the round”. “They have got to make sure they deliver measured progress towards, not away from, parity of esteem,” he said.