Prince Charles was last night urged to stay out of the debate over homeopathy on the NHS, amid claims that he had lobbied the Health Secretary in favour of the controversial alternative treatment.

Labour MPs reacted with fury at the revelation that the heir to the throne had met Jeremy Hunt last week, with NHS support for homeopathy believed to be on the agenda. The disclosure of the Prince’s latest communications with senior politicians came days after judges ruled that the public has no right to know the contents of 27 letters he had written to ministers over several years, in an attempt to influence policy decisions.

Prince Charles is a long-term advocate of homeopathy, which involves treating patients with highly diluted substances “with the aim of triggering the body’s natural system of healing”. Mr Hunt once told a constituent that “it ought to be available [on the NHS] where a doctor and patient believe that a homeopathic treatment may be of benefit”.

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Earlier this year the Government’s new chief scientific adviser, Sir Mark Walport, dismissed homeopathy as “nonsense”, but critics have complained that the NHS is still spending millions of pounds a year on a therapy they claim has no effect on patients.

Despite Mr Hunt’s support for homeopathy, Prince Charles is believed to be frustrated with the Government’s failure to force through a register of practitioners of herbal and Chinese medicine.

But the Birmingham Labour MP Steve McCabe said it was “strange” that the heir to the throne should be able to lobby the Health Secretary on such a controversial issue. “It is even more extraordinary that he should be allowed to do this in secret ... I can’t see how it isn’t in the public interest for the rest of us to know,” he said. His colleague, Paul Flynn, claimed the Prince had a duty to remain neutral, particularly over a hugely controversial issue involving public spending and the health of the nation. “People are entitled to believe what they want, but having the heir to the throne attempting to influence the spending of precious NHS resources on a service he probably doesn’t use at all is ludicrous ... Prince Charles should not be interfering; he is in training for his role as monarch and the first lesson is to put a bandage round his mouth and to keep it there at all times,” he said.

Homeopaths claim they can treat a range of conditions. But a critical report from the Health Select Committee in 2010 raised questions over its effectiveness. It said: “Homeopathy should not be funded on the NHS.” Governments have since avoided endorsing it, but clinics and trusts are free to offer homeopathic treatments.

The Tory MP David Tredinnick, a supporter of homeopathy who also sits on the Health Select Committee, said he was not concerned about Prince Charles’s intervention, as “he is probably as well placed as anybody in the country to comment on this”. Speaking on the BBC, Mr Tredinnick said: “We should do what they do in the rest of the world, which is to take [homeopathy] seriously.”

But David Colquhoun, a pharmacologist at University College London, said homeopathy was “utter nonsense”. “Homeopathic remedies contain nothing whatsoever. The Americans have spent $2bn investigating these things … they haven’t found a single one that works,” he said.

Clarence House confirmed the Prince had met Mr Hunt last week, but neither they nor the Department of Health would give details of the discussions.