The letter was signed by Professor Michael Baum, emeritus professor of surgery at University College London and 12 other leading medics, and was timed to coincide with a speech given by Prince Charles yesterday, in which he told the World Health Organisation in Geneva that alternative medicine should have a more prominent place in health care.
The signatories took particular issue with homeopathy, which they called "an implausible treatment for which over a dozen systematic reviews have failed to produce convincing evidence of effectiveness"
But they also criticised efforts to promote CAM as a component of healthcare on the grounds that some products are "known to cause adverse effects" and others "have no demonstrable benefits".
Such products were unspecified in the letter, but may include the herbals St John's wort, which may interact with some prescription medicines, and Echinacea, which has a large following as a common cold preventative but studies of its efficacy have so far been inconclusive (possibly as a result of dosage issues).
"While medical practice must remain open to new discoveries for which there is convincing evidence, including any branded as 'alternative', it would be highly irresponsible to embrace any medicine as though it were a matter of principle," they wrote.
"At a time when the NHS is under intense pressure, patients, the public and the NHS are best served by using the available funds for treatments that are based on solid evidence."
Amongst the signatories is Professor Edzard Ernst, professor of complementary medicine at the University of Exeter.
Professor Ernst has previously said: "If an effective CAM treatment or preventative measure emerged (say, a herbal medicine) it would instantly be taken up by mainstream oncology, as has happened with taxol, which comes from the yew tree."
Prince Charles, meanwhile, last night urged every country to come up with a plan to integrate conventional and alternative medicine into the mainstream.
He did not refer to the letter in his speech, but Michael Dixon, a GP and trustee and spokesperson for the Prince's Foundation for Integrated Health - as well as chairman of the NHS Alliance, noted that none of the signatories are directly involved in primary care.
In a media statement, he said they "have a slightly old-fashioned view".
A report published last year in the New England Journal of Medicine held that use of herbal medicines in the UK is amongst the lowest in Europe, and few GPs prescribe them.
At the other end of the scale German health insurance providers reimbursed US$283 million for prescriptions of ginko, St John's wort, mistletoe, saw palmetto, ivy, hawthorn, stinging nettle root, myrtol, phytosterols and curcurbita in 2003.
French insurers paid out $91 million in partial reimbursements for ginko, saw palmetto and pygeum, with a total value of $196 million.
Almost $5 billion (at manufacturers' prices to wholesalers) was spent on over-the-counter herbal medicines in all European countries in 2003.