Government ambitions to deliver more NHS services seven days a week without increasing the wage bill have been branded an ‘attack on hard working nurses’.

Health minister Dan Poulter has asked the NHS Pay Review Body to make “observations” on “affordable out of hours working arrangements”. In a letter sent to the body on Friday he said reforms to pay were “crucial to this vital area of service provision”.

There has been a growing drive to offer more hospital services at weekends and out of hours after several studies found patients admitted on weekends and bank holidays were more likely to die than those admitted during the week.

Health service commissioners are also keen that more community services are available round the clock to improve quality of care and ease pressure on busy acute hospitals.

Dr Poulter wrote: “There is a strong case for seven day services on the grounds of both patient safety and quality of patient care.

“For 2015-2016 the NHS Pay Review Body is asked to make observations on the barriers and enablers within the [Agenda for Change] pay system for delivering healthcare services every day of the week in a financially sustainable way, i.e. without increasing the existing spend.”

However, Royal College of Nursing chief executive and general secretary Peter Carter said the government’s ambitions could only be achieved by nursing staff working more night shifts and weekends “for no additional pay”.

He said: “This is an attack on hard working nurses and healthcare assistants, adding insult to injury and showing that the government’s declared support for the NHS is nothing but empty rhetoric.”

Earlier this year the government rejected the pay review body’s recommendation that all NHS staff should get a 1 per cent pay rise in 2013-14. Instead, only staff not receiving an incremental pay rise under Agenda for Change would get the 1 per cent boost.

In previous years the body’s independent recommendations on NHS pay have been credited with avoiding potentially unpleasant clashes between the government and the unions over pay.

However, the government has also said it would not be asking the body to make a recommendation for 2015-16, leading to warnings of the review body’s imminent demise from unions.

Mr Carter said: “It seems that the review body is being politicised and the government will only accept recommendations that it likes.

“The government must not, and should not use the [body] for its political ends in this way. RCN members are very angry about this interference and it will only serve to strengthen our political campaign.”

The RCN is the only major union representing nurses not planning to ballot its members on the pay offer. Unite, Unison, GMB and the Royal College of Midwives are all seeking members views on whether to strike or take industrial action short of a strike.