More than 250 writers have written to the Welsh government, warning of the severe impact of planned reductions to support for literary culture

Slashes to the Welsh Books Council budget will have a “significant and deleterious impact” on literature from Wales, according to a campaign mounted by some of the country’s highest-profile authors protesting the Welsh government’s plans.

More than 250 British and Wales-based writers have put their names to a letter to Welsh deputy culture minister Ken Skates attacking the proposed cut of 10.6% to the Welsh Books Council, which they say “undermine[s]” and “undervalue[s]” writing from Wales. The signatories include Philip Pullman, Sarah Waters, the national poet of Wales, Gillian Clarke, the TS Eliot prize-winning poet Philip Gross, the Dylan Thomas prize winner Rachel Trezise and the Man Booker-longlisted Patrick McGuinness.

The cuts, they say, equate to a financial shortfall of £374,000 – more than twice the size of planned cuts to other cultural organisations. It will, they say, have a severe impact on “a vibrant, bold, and highly acclaimed English-language publishing industry, which, although undeniably small, has proved its merits over the past decade – and which has a wide reach beyond Wales”.

A petition calling for the “unprecedented” cuts to be abandoned has also been launched and already has over 650 signatures, including Pullman and Waters.

Clarke said she was “ashamed that such cuts to publishing are even considered”. “Wales holds the oldest continuous literature in Europe. Our stories are British treasures,” she said. “Poetry is the national art. The earliest known British poets composed in Welsh. The Welsh people were the first literate proletariat. The Bible, translated into Welsh before English, taught the people to read. At a time of a crisis in literacy among the most deprived communities, we need our writers, and their books, more than ever.”

More than 250 Welsh-language writers, who are also affected by the cuts, have also rushed to sign a letter to the Welsh Assembly government, laying out their concerns over the “disproportionate” cut which they say “will have far-reaching consequences for Welsh writers and publishers”. Signatories include Welsh-language novelist and playwright Caryl Lewis, and former national poets of Wales Gwyneth Lewis and Gwyn Thomas.

There is a particular boldness of imagination that is alive in the Welsh culture that needs supporting Philip Gross

The concerted campaign also includes Welsh publishers, with names including Seren, Honno and Parthian banding together to tell the Welsh government that without support, “it would be increasingly impossible for writers in Wales to be published in Wales to any level of commercial competition with the publishing behemoths in England”.

Their letter points out that after a decade of standstill funding, grants to Welsh publishing in English will have been slashed by 21%, or £158,050, in the last three years if the plans go ahead. The proposed 10.6% cut this year would see Welsh-language grants reduced by £187,000, English-language grants reduced by £76,500, and the core funding of the Welsh Books Council reduced by £110,500.

Speaking to the Guardian, Gross, who won the TS Eliot prize in 2010 for his collection The Water Table, said that “in an age when the diversity and richness of the UK is so important, it seems perverse to be starving one of the sources of that richness”.

Gross, who is not Welsh but who has lived in Wales for 11 years, said the culture there “has enriched my own writing immeasurably”. In 2010, Gross won the Wales book of the year award for his collection I Spy Pinhole Eye, published by small Welsh publisher Cinnamon Press, an organisation Gross called “gallant and enterprising”.

“There is a particular boldness of imagination that is alive in the Welsh culture that needs supporting,” said Gross. “Never think the world of Welsh writing is a small world – it’s a whole world of its own – and it’s European as well as British. But so many of these enterprises are just living on the edge of viability. They’ve made their homes on the very edge of the steep cliff of economic viability. It doesn’t take very much encouragement and support, but they do need some … The sums involved in the grand scheme of things are not huge, but in the light of these organisations and enterprises they are life and death. This is not about trimming off the fat; we are lean mountain sheep already.”

McGuinness, whose novel The Last Hundred Days won the Wales book of the year award, and was longlisted for the Booker and shortlisted for the Costa, slammed the cuts as “absolutely savage”. “[They mean that] authors will stop getting taken on, and publishers are going to get laid off,” he said. “The arts don’t require that much money, and they pay a huge dividend, so what is happening at the moment is really shocking, and it’s quite clearly to do with the current Welsh government’s philistinism.”

In their letter, the authors say the cuts will put Welsh publishers under “agonising pressure” as they face “agonising choices” to publish fewer books.

Pointing to Wales’s “long and deserved reputation for achievement in its literary endeavour” through events such as the international celebration of Dylan Thomas, they write that “Dylan Day would seem to make little sense in a context which sees the contemporary output of great writing from Wales so undermined and apparently undervalued by its custodians”.

“Great writing from Wales speaks of cultural pride and ambition, which are the twin markers of any confident nation. We therefore strongly urge you to reconsider these cuts and the impact they will have – not simply over the immediate years ahead, but as a long-term political legacy,” the writers tell Skates in their letter.

“We understand that we live in a time of austerity, but believe that in such challenging times this most vulnerable but crucial platform for artistic enterprise should be especially protected. The publishing industry of Wales is now facing a cut that is approximately double that of other prominent bodies which provide services to the culture of Wales. This is unjust and amounts to self-sabotage.”

A spokesperson for the Welsh government said that its budget had been cut significantly since 2010, with further “real-term cuts” to come as a result of the UK government’s spending review. “As a result of these financial constraints, difficult decisions have had to be made in order to protect the services that people rely on the most. We’re in discussions with the Welsh Books Council about how they will make efficiency savings, while prioritising and targeting its grant programmes to support the publishing industry in Wales and protect jobs as far as possible,” said the spokesperson. “Meanwhile, the minister for economy, science and transport has agreed additional in-year funding to the Welsh Books Council to undertake urgent work on its headquarters and distribution centre and upgrade the Council’s IT systems. This will of course benefit the whole publishing industry in Wales.”

Authors Jon Gower and Tony Bianchi will be meeting Assembly members on Wednesday to speak on behalf of the writers of Wales, both Welsh- and English-language.