A group of Britain’s leading authors has accused Tesco of using “deeply chilling” tactics to silence its critics.

Nick Hornby and Mark Haddon are among the writers who have signed a letter in The Times today condemning the supermarket for prosecuting a Thai business leader for making a speech that decried Tesco’s expansion. If the supermarket is successful Jit Siratranont could be jailed.

Hornby and Haddon – together with Marina Lewycka, the author of A Short History of Tractors in Ukrainian, and Deborah Moggach, who wrote Tulip Fever – have also put their names to a longer open letter arguing that a criminal libel prosecution and two civil actions against journalists represent a breach of their human rights.

The authors threw their weight behind the protest – organised by English PEN, a campaign group for freedom of expression – despite the combined sales of their books through Tesco being estimated at £2.5 million, according to The Bookseller magazine.

The letter states that Tesco Lotus, the supermarket’s Thai operation, acted with disproportionate vigour by accusing Mr Jit, a former Thai MP, of criminal libel, which can carry a sentence of two years in prison and a fine of £16.6 million. Mr Jit, who is vice-general secretary of the Thai Chamber of Commerce, made a speech accusing Tesco Lotus of expanding aggressively at the expense of small retailers.

Tesco Lotus, which is 99 per cent owned by Tesco, is pursuing a civil action for £1.6 million against Kamol Kamoltrakul, a freelance journalist who earned £16 for his column in which he criticised the supermarket. A second journalist, Nongnart Harnvi-lai, is also being sued after concluding an article with the words: “Ha, Tesco Lotus doesn’t love Thais.”

The British authors said that the supermarket’s action “sends a deeply chilling message to others who seek, quite legitimately, to discuss Tesco’s impact on their local economy”.

Organisations have the right to protect their reputations, but only if it is proportionate, they wrote. “We urge“ you to drop all actions in Thailand, and to impress your critics with the force of argument, not the threat of imprisonment.”

Lord Lester of Herne Hill, QC, a human rights expert, said that he was outraged by Tesco’s actions. “It is deplorable for Tesco to raise the sword of Thai libel law to suppress honest criticism of their policies and practices in Thailand, especially since they would be unable to succeed in similar proceedings in this country,” he said.

A spokesman for the supermarket said that Tesco stood by its Thai subsidiary, which would have informed its superiors in Britain of its actions. “All three of these actions follow a sustained period of attack on Tesco Lotus in Thailand. It is our fervent wish to reach agreement. We are seeking a public apology. It is very regrettable that we have had to take legal action in Thailand. We had hoped that the individuals concerned would apologise for the false and highly damaging allegations they had made about our business over a sustained period of time but despite numerous attempts to get them to set the record straight, this has not happened.

“These cases are framed in a way appropriate under Thai law but what we want is an apology and a retraction of claims which were false, damaging to our reputation and misleading to our Thai customers and staff. We are still hopeful that these apologies will be forthcoming and that the matters can be resolved by agreement, without the need to resort to the courts.”

Jonathan Heawood, director of English PEN, said that Tesco’s actions had more in common with a tyrant than a supermarket. “The offence of criminal defamation is routinely used by dictators, not corporations. Its apparent deployment now by a UK-based company or its Thai subsidiary, which prides itself on its support for producers and consumers, sends an appalling message around the world.”

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