Over 200 noted authors, including Salman Rushdie and Neel Mukherjee, have asked British Prime Minister David Cameron to raise the issue of "rising climate of fear" and "growing intolerance" in India during his talks with his counterpart Narendra Modi.
Booker Prize winner Rushdie, recent Booker prize shortlisted British-Indian author Mukherjee and other well-known names like Ian McEwan and Hari Kunzru are among the signatories of an open letter to Cameron.
"We, the undersigned, are extremely concerned about the rising climate of fear, growing intolerance and violence towards critical voices who challenge orthodoxy or fundamentalism in India... we urge you to engage with Prime Minister Modi both publicly and privately on this crucial issue," the letter says.
"Please speak out on the current state of freedom of expression in his country, urging him to stay true to the spirit of the democratic freedoms enshrined in India's Constitution," it adds.
The letter was published by PEN International -- a worldwide membership organisation for prominent literary figures, and signed by members of its centres in England, Wales and Scotland.
It points to the recent murders of the intellectuals Malleshappa Madivalappa Kalburgi, Govind Pansare and Narendra Dabholkar, and to the protests that have seen at least 40 Indian writers return literary awards to the Sahitya Akademi, the National Academy of Letters, in condemnation of its silence over the attacks.
The writers' letter continues: "The protests have grown beyond the community of Indian writers of all languages. Scientists, artists, film-makers, academics, scholars, and actors have either complained (about) the climate of intolerance or returned awards on a scale unprecedented in India.
"In line with the United Kingdom's stated commitment to promoting human rights, we ask that you raise the above issues with Prime Minister Modi and urge him to provide better protection for writers, artists and other critical voices and ensure that freedom of speech is safeguarded. Without these protections a democratic, peaceful society is not possible."
Carles Torner, executive director of PEN International, said: "Prime Minister Modi's visit to the UK is an opportunity... to ensure that the disturbing trend of intolerance towards dissent and criticism in India is raised."
Jo Glanville, executive director of English PEN, added: "Writers in the UK are standing in solidarity with their colleagues in India. There has been an unprecedented wave of protest following ongoing threats to writers in India and the government's failure to protect freedom of expression in an increasingly hostile climate."
Thursday's letter is the second from the PEN International in less than a month over the issue of "rising intolerance" in India. On October 17, writers from 150 countries expressed solidarity with dissenting Indian authors and artistes who returned their prestigious awards.
The latest letter adds to other voices of protest on the sidelines of the visit with a "day of protest" planned on Thursday by the 'Modi Not Welcome' campaign as well as a protest organised by CasteWatchUK outside Downing Street and then at Parliament Square.
Another group of protesters will be demanding that the Indian government lift the ban on the documentary India's Daughter by British filmmaker Leslie Udwin.
Around 46 MPs, including leader of the opposition Labour party Jeremy Corbyn, have also signed a parliamentary motion asking Cameron to raise human rights issues with the Indian government.
The protests might be a dampener for Modi's much-anticipated maiden visit to the UK that will see him holding talks with top British leadership including his counterpart David Cameron besides having lunch with the Queen and addressing the Indian diaspora in a mega address.
