The head of the government's drugs rationing body has claimed that a number of NHS trusts are "breaking the law" by denying patients access to approved treatments and drugs to save money.

Sir Michael Rawlins, the chair of the National Institute for Health and Clinical Excellence (Nice), said there were many examples of primary care and NHS hospital trusts using "delaying tactics in order to circumvent the legal obligations they have to provide treatment and drugs recommended by Nice within three months". Rawlins urged doctors to "show leadership" by naming primary care and hospital trusts they believe are "breaking the law" by denying patients treatments to which they are entitled. Set up by the government in 1999 as an independent organisation, Nice decides which drugs and treatments are available on the NHS in England and Wales. Rawlins claimed there were "numerous" trusts stalling to allow them to spend money on other things.

He shone a spotlight on the issue last week in the Health Service Journal after reporting the problems many patients were having accessing a Nice-approved treatment, called dexamethasone intravitreal implants, for the common eye condition retinal vein occlusion.

Nice concluded in July 2011 that the implants, that are installed every six months and help prevent sight deterioration, represented a cost-effective use of NHS resources".

A survey of 125 hospital trusts in England with eye health services conducted by the Royal National Institute of Blind People in February found that of the trusts that responded, 45 were providing a full service and 37 were providing either a restricted service or no service.

In his article, Rawlins said he had advised the RNIB to make an application to the high court and seek a judicial review.

He told the Today programme that it was a "slightly tongue-in-cheek" suggestion since his point was the case would never reach court because trusts would be advised by their lawyers that they had an "indefensible case".

But he said individual patients should not be forced to pursue the legal route to access treatments and drugs to which they were entitled.

He said the problem was not uncommon and called for clinicians to show more "backbone" and leadership to get the problem sorted, despite the difficulties he acknowledged this might cause with their employers.

Doctors "should whistleblow and they should make it abundantly clear to the public that their trust is in breach of the law," he said.

He added: "Patients shouldn't have to go to court to get treatments for which they are entitled. It really is wrong to think that that's the case. I would hate it if that were the case. Trusts should do the right thing and make these treatments available."

Steve Winyard, head of policy and campaigns at the RNIB, said the charity was seriously considering seeking a judicial review against two PCTS to ensure patients could benefit from the treatment.

"It is not something we would do lightly," he said. "It is something we do not want to do."

Labour urged the health secretary, Andrew Lansley, to investigate claims that patients were unlawfully being denied drugs.

Diane Abbott, shadow public health minister, said: "This government is letting patients down – crude cost-cutting in the NHS has seen a postcode lottery running riot, which is totally unacceptable. Patients in some areas are being flatly denied drugs they deserve, whilst in other areas the drugs are limited to a small number of patients. People should have quick and ready access to drugs they need and Andrew Lansley needs to investigate these unlawful tactics."

Michael Dixon, chair of the NHS Alliance, which brings together GP consortia, PCTs, clinicians and managers in primary care, said primary care trusts, like the clinical commissioning groups that will replace them, are forced to juggle other legal responsibilities, such as keeping within budget. In the process of accepting local priorities, sometimes "one priority will come over another", he said.

"If they can show that there are other priorities and the clinicians are behind them, and especially if they've got their local people behind them, which the clinical commissioning groups because they are clinical organisations will be able to do in the future, we will find sometimes the money will go into other things" , he told Today.

Dixon said that "no one is trying to save money for the sake of it" but he said that sometimes there were most cost effective ways of treating patients, such as preventative treatments, rather than cures advocated by Nice.

"There are some Nice approved drugs which may be cost effective but there may be other ways that are better."

He refuted the criticism that clinicians failed to speak up. "They have plenty of backbone".

Clinicians had to balance not only patient needs and wants, the science and their own clinical opinions but also assess the needs of the patient in front of them with those of all the other patients on their books. "As clinicians we have to make these balances," he said.

He said that the last thing the NHS needed was the suggestion - albeit tongue in cheek - of further litigation in the NHS, which was already spending a £1bn on legal cases.

The British Medical Association said doctors should have no hesitation in speaking out on behalf of patients.

A BMA spokesperson said: "Doctors play a key role as an independent advocate for their patients and like other healthcare professionals base their decisions on what is best clinically for the individuals under their care. If they feel treatment decisions are being taken that are not based on clinical need they should have no hesitation in challenging and speaking out about the matter."

The NHS Confederation, the umbrella body representing all organisations that commission and provide NHS services, said the NHS was striving to maintain high quality care in the face of an "unprecedented financial challenge".

David Stout, NHS Confederation deputy chief executive of the NHS Confederation, said NHS commissioners and providers need to resolve such issues quickly to make sure patients get access to the care they need.

"However, we must remember the reality is that every NHS organisation has a finite amount of money available. Every new treatment covered and funded under a NICE technology appraisal means fewer resources for other treatments.

"NHS organisations are faced with the difficult challenge of achieving the best outcomes and highest quality care for patients while balancing their budgets."

He added: "We need to be open and honest with the public about what the consequences of this financial challenge are, and the fact that trade-offs will be required if we are to improve standards of care while keeping the NHS affordable."