The , published in The Times today, is part of a campaign organised by the writers' group , which supports freedom of speech.
It has been written in response to Tesco's legal action against a journalist and a Thai businessman, who have both criticised expansion plans for Tesco Lotus in Thailand.
According to The Times, Tesco Lotus is taking the businessman Jit Siratranont to court, accusing him of criminal libel over a speech he made that criticised Tesco's expansion in Thailand at the expense of small retailers. If he is found guilty, he could spend time in prison.
The letter has been signed by authors Hornby, Haddon, Joanne Harris, Deborah Moggach, Marina Lewycka; along with Anthony Lester, QC, and two PEN supporters, Lisa Appignanesi and Jonathan Heawood. It says that Tesco is sending "an unsettling message around the world" with the court case.
The letter says: "As writers we greatly value the tradition of free speech in Britain, and we would like to think that a leading international business such as Tesco would be concerned with exporting these values along with its groceries.
"We urge Tesco to impress its critics with the force of argument, not the threat of imprisonment."
A Tesco spokesman has told The Times that the company was taking action after "a sustained period of attack on Tesco Lotus in Thailand", and that the company hoped to receive an apology.
The spokesman said: "We are still hopeful that these apologies will be forthcoming and that the matters can be resolved by agreement, without need to resort to the court."