Comedians, writers and broadcasters join forces with leading scientists today in calling for an urgent review of English libel laws, as a best-selling author appeals against a law suit against him.

Simon Singh, the author of Fermat’s Last Theorem, is being sued by the British Chiropractic Association (BCA) over an article in which he criticised the promotion of spinal manipulation therapies for children’s illnesses such as asthma.

Dr Singh confirmed yesterday that he will carry on fighting his case, despite a preliminary court judgment against him and legal costs of more than £100,000.

The case has triggered a wider campaign among scientists, lawyers, journalists and politicians who say that current libel laws are strangling freedom of speech. The cause has support from Stephen Fry, Martin Amis, Ricky Gervais and Carol Ann Duffy, the Poet Laureate, among others.

Richard Dawkins, the evolutionary biologist and author; Lord Rees, Professor of Astrophysics at Cambridge; and Baroness Kennedy of the Shaws, the human rights lawyer, are also among more tham 100 eminent figures who are endorsing a campaign statement that “the law has no place in scientific disputes”.

The case against Dr Singh was brought after he wrote an article for The Guardian in which he criticised the BCA for supporting members who claim that chiropractic treatments can treat children’s colic, sleeping and feeding problems, frequent ear infections, asthma and prolonged crying.

Dr Singh described the treatments, for which he noted there was not a lot of evidence, as “bogus” and criticised the association for “happily promoting” them.

Last month in the High Court Mr Justice Eady gave a preliminary ruling on the meaning of the words used in Dr Singh’s piece. He held that the phrase implied that the association was being consciously dishonest, an interpretation that Dr Singh argues was not implied, given the context of his article.

He intends to apply to the Court of Appeal over this ruling next week. If denied permission to appeal, he said he would consider taking the case to the European Court of Human Rights.

The signatories to the wider campaign — including journalists from The Times and The Guardian — call upon the British Chiropractic Association to discuss the evidence for chiropractic in the public domain instead of the courts.

Their statement adds that the current libel laws can “severely curtail the right to free speech on a matter of public interest”.

“It is already widely recognised that the law is weighted heavily against writers: among other things, the costs are so high that few defendents can afford to make their case.”

The cost of fighting libel actions in England and Wales is 140 times the European average.

London has become notorious as “the libel capital of the world” after a series of high-profile lawsuits, even relating to international publications that were unlikely to have been read in Britain.

Comparing the English libel system to a “high-stakes poker game”, Dr Singh said that he was lucky to have the financial means to pursue his case, after writing at least three bestsellers.

The cost of going to trial could exceed £1,000,000, he said, while settling the case would cost more than £200,000, as he would have to pay the BCA’s costs as well as his own.

Offers of support and money “have been flooding in”, he said, but he asked that any donations should be made to Sense About Science, the not-for-profit group that is co-ordinating the campaign.

“Everyone agrees that there is something fundamentally wrong with the English libel laws, which have a chilling effect on journalists, whether they write about science or anything else,” he said. “Hence, I am delighted that so many individuals and organisations have come together to launch a campaign with Sense About Science to highlight how the English libel laws clash with the right to discuss science in a frank and fair way.”

Dr Singh is co-author, with Professor Edzard Ernst of Exeter University, of a book on complementary medicine called Trick or Treatment.

Richard Brown, the vice-president of the BCA, said that the association had sued Dr Singh “only as an act of last resort”.

“He published what the Association believed were libellous remarks ... The BCA is fully supportive of scientific debate and this should be a fundamental right,” he said. “However, with rights come responsibility and scientists must realise that they cannot simply publish with impunity what they know to be untrue and libellous.”

Simon Singh is due to speak at The Times Cheltenham Science Festival on Saturday