On the eve of the Sochi winter Olympics, as the eyes of the world turn towards Russia, an assembly of more than 200 leading international authors – including Salman Rushdie, Günter Grass, Margaret Atwood and Jonathan Franzen – has formed to denounce the “choke hold” they say the country’s anti-gay and blasphemy laws place on freedom of expression.

The open letter condemns the country’s recently passed gay propaganda and blasphemy laws, which respectively prohibit the “propaganda of non-traditional sexual relations” among minors and criminalise religious insult, and its re-criminalisation of defamation. The three laws “specifically put writers at risk”, say the authors, and they “cannot stand quietly by as we watch our fellow writers and journalists pressed into silence or risking prosecution and often drastic punishment for the mere act of communicating their thoughts”.

Grass is joined as a signatory by three fellow Nobel laureates, Wole Soyinka, Elfriede Jelinek and Orhan Pamuk, and by internationally acclaimed writers from over 30 countries, including Ariel Dorfman, Carol Ann Duffy, Edward Albee, Julian Barnes, Ian McEwan and Neil Gaiman. Russia’s foremost contemporary novelist, Lyudmila Ulitskaya, is also a signatory to the letter.

Rushdie described the campaign as “essential”, telling the Guardian that it is “incredibly important to Russian writers, artists and citizens alike”.

“The chokehold that the Russian Federation has placed on freedom of expression is deeply worrying and needs to be addressed in order to bring about a healthy democracy in Russia,” said the Booker prize-winning novelist, author of Midnight’s Children and The Satanic Verses.

Adding his voice to the protest, Neil Gaiman wrote: “I believe that free expression – freedom of speech, freedom to write, to argue, to disagree – is the most important freedom we have as human beings. I hate to see that being stifled in Russia: the solution to speech and writing that offends you is to speak and write about it in your turn, not to criminalise it or to try and eradicate it … I hope that Mr Putin reads the open letter; I hope he changes course.”

Ulitskaya, the first woman to win the Russian equivalent of the Booker, said that Russian authorities were attempting to impose “a cultural ideology that, in many respects, mimics the style of Soviet-era propaganda”.

“Like many Russian citizens, I am deeply concerned about the increasing restrictions on freedom of speech in my country, about the ever-expanding legislation and arbitrary bureaucracy that affect all aspects of Russian life,” she said. “I am frightened by the judicial system’s increasing dependence on these very authorities. Because of this, I signed PEN International’s open letter to the Russia authorities protesting their increasingly regressive approach to freedom of expression.”

Two hundred and seventeen fellow signatories to the open letter, organised by PEN International, are urging the Russian authorities to repeal the country’s laws that “strangle free speech”.

They also want Russia to recognise its obligation under the International Covenant on Civil and Political Rights “to respect freedom of opinion, expression and belief – including the right not to believe – and to commit itself to creating an environment in which all citizens can experience the benefit of the free exchange of opinion”.

“A healthy democracy must hear the independent voices of all its citizens; the global community needs to hear, and be enriched by, the diversity of Russian opinion,” they write. Other key authors to have put their names to the letter include Middlesex author Jeffrey Eugenides, Jostein Gaarder, the Norwegian author of Sophie’s World, Chinese novelist Ma Jian, the Turkish writer Elif Şafak and the Scottish author Ali Smith.

The letter is part of PEN International’s worldwide campaign to highlight what it calls “the draconian restrictions placed on free expression” in Russia since Vladimir Putin returned to office in May 2012. Although the writers’ organisation welcomed December’s release of 2,000 prisoners – including two members of the band Pussy Riot and the Arctic 30 environmental protesters – it said they should “never have been arrested in the first place”, and called the amnesty “part of a politically-motivated move to soothe criticism ahead of the Sochi Games during which a huge wave of protest is expected in Russia and beyond in response to Putin’s increasingly repressive approach to freedom of expression”.