Money earmarked for the costs of reorganising the NHS could pay to prevent the loss of 6,000 nursing jobs, Labour claims.

Labour leader Ed Miliband will use the figure to renew pressure on the government to drop its controversial shake-up after warning there were just three months to save the NHS.

According to Opposition calculations, more than 3,500 nursing jobs have been lost since the government came to power and another 2,500 are under threat.

The £1.7bn set aside to pay for the changes in the Health and Social Care Bill would cover the £748m cost of protecting all of those jobs, it believes.

Mr Miliband will use a visit to a Kent hospital to step up his campaign against the bill.

He is expected to say: “In tough times and with little money around, the very first priority should be to protect the frontline NHS.

“Instead we have a government blowing a vast amount of money on a damaging top-down reorganisation at the same time as it is cutting thousands of nurses.

“Labour’s priority is protecting the front line, not a pointless and damaging reorganisation of the NHS.

“So we are calling for the bill to be scrapped, and for some of the money set aside to fund this reorganisation to instead be made available to the NHS to protect the thousands of nursing posts either already cut or set to be cut in the coming years.

“It is a clear and simple choice for the government: by stopping this damaging reorganisation we can fund 6,000 nurses.

“In opposition David Cameron told people he could be trusted to protect the NHS. In government he has put Tory free-market ideology ahead of basic patient care.”

Shadow health secretary Andy Burnham added: “In just over 18 months in government, the coalition has taken a successful and confident NHS and turned it into an organisation that’s demoralised, destabilised and fearful of the future.”

The bill is due to return to the House of Lords this week for further debate.

Mr Miliband said it opened the health service to a “free market free-for-all” that would put the principles of the NHS at risk.

“It is not too late to stop this bill. We have three months to prevent great harm being done to the NHS,” he wrote in the Observer.

“Now is the time for people of all parties and of none, the professions, the patients and now peers in the House of Lords to work together to try to stop this bill.”

Royal College of Nursing chief executive Dr Peter Carter said: “Our Frontline First campaign has already identified over 48,000 NHS posts at risk in England alone.

“These figures are further evidence, if it were needed, that the extensive NHS reorganisation set out in the Health and Social Care Bill is a costly distraction from the major challenges faced by the NHS. The turmoil of stopping the Bill is outweighed by the turmoil of allowing it to continue, and we would urge peers to vote against the Bill when it is put before them again this week.”

Health minister Anne Milton said: “Labour’s accusations are wrong on all counts.

“Since the election we’ve cut admin staff by 15,000 and the total number of clinical staff has remained the same.

“If we were not proceeding with modernisation in the NHS, by the end of this Parliament there would be £1.5bn not available to support services and frontline staff.

“Stopping the reforms now would mean cutting nursing posts. The shape of staffing in the NHS is changing and the increase in doctors and therapists relative to nurses reflects that.

“But nursing numbers continue to be at highest-ever levels in areas where they are needed. The ratio of nurses to the number of acute beds in hospital has improved significantly over the last 18 months.”