Giving homeopathic remedies to patients on the NHS is unethical and a dubious use of public money, scientists and doctors told MPs today.

The treatments, which are licensed by the government and offered through several NHS hospitals, have insufficient clinical evidence to support them, they said.

The criticisms were raised in an inquiry held by the Commons cross-party science committee to investigate the strength of scientific evidence behind government policy on homeopathic medicines.

"If the NHS commitment to evidence-based medicine is more than a lip service, then money has to be spent on treatments that are evidence-based, and homeopathy isn't," said Edzard Ernst, a professor of complementary medicine at the Peninsula medical school in Exeter.

Homeopathic treatments are usually made by diluting a substance so much there may be no molecules of the original ingredient left. Homeopaths maintain that water retains a memory of the substance, which has a therapeutic effect. Most scientists contend the treatments are no better than placebos or sugar pills.

"If you prescribe a drug to patients that you know has no efficacy, on a basis which is essentially dishonest with a patient, I personally feel that is unethical," Dr James Thallon, medical director at the NHS West Kent primary care trust told MPs. "We have taken the view about where the balance of the scientific community's opinion is on homeopathy and, to me and my colleagues, it's pretty clear."

Thallon cut funding to Tunbridge Wells homeopathic hospital in 2007 after deciding that more proven medications have priority. The NHS spent £12m on homeopathic remedies between 2005 and 2008, money many critics said the health service could not afford.

Peter Fisher, a medical doctor and practising homeopath at the Royal London Homeopathic hospital, defended the treatments, arguing they gave "more bang for the buck" compared with conventional medications. "I practise it because I think it works. I wouldn't use it … if I thought I was conning the patient," he said.

Unlike conventional drugs, homeopathic treatments can be sold without being proven to work in clinical trials. Instead, they can be marketed for mild conditions if homeopaths broadly agree the treatment relieves symptoms of a condition. Many scientists believe this exemption should be removed because it is misleading and undermines the credibility of pharmacists and the government's regulatory body, the Medicines and Healthcare products Regulatory Agency.

Paul Bennett, standards director at Boots, the chemist, said the company would continue to stock homeopathic treatments. "I have no evidence to suggest they are efficacious. It's about consumer choice and a large number of our customers think they work," he said.