Prize-winning novelists Orhan Pamuk and Kiran Desai have pulled out of Sri Lanka's main literary festival.
The couple are currently at Jaipur literature festival in India and were due to go on to Galle, in southern Sri Lanka, for the event next week.
The Galle Literary Festival says they are now unable to attend because of Indian re-entry visa regulations.
Some rights groups have urged authors to boycott the event because of Sri Lanka's restrictions on free speech.
Reporters Without Borders said it was "highly disturbing that literature is being celebrated in this manner in a land where cartoonists, journalists, writers and dissident voices are so often victimized by the current government."
Noam Chomsky, Arundhati Roy and Ken Loach are among those backing a boycott.
But there is no indication that the campaign had anything to do with the withdrawal by Nobel laureate Mr Pamuk or his Indian partner Ms Desai, a Booker prize winner.
Organisers say they were unable to resolve difficulties with India over the tourist visa restrictions, under which Mr Pamuk would be unable to re-enter the country within two months.
A statement by the festival quoted emails from the couple reflecting their regret.
"I am very sorry for and frustrated about this decision… I looked forward to seeing the beauties of Sri Lanka very much," the Turkish author is said to have written.
Ms Desai's missive apparently said: "Nobody could be sadder than me. I love Sri Lanka and had a super time the last time I was in Galle."
Rights groups say at least 17 journalists and media workers have been killed in Sri Lanka in the last decade, and others have been threatened, imprisoned or fled the country.
But the founder of the Galle festival Geoffrey Dobbs says the event is important as a platform for free speech.
"The Festival is one of the few forums in the country which actively promote lively and spirited discussions," he said. "We want this to continue... and we will always welcome any writers and journalists to use the festival as a platform to air these issues."