More than 400 international authors, artists and academics, led by award-winning poet George Szirtes and novelist Colm Tóibín, have criticised the Hungarian government over a law that could close a university founded by billionaire philanthropist George Soros.

In an open letter, also signed by poets Pascale Petit and Christopher Reid, novelists Meg Rosoff and Toby Litt and composer Ana Silvera, the group condemns a law passed on 10 April that could close the Central European University, which Szirtes claimed is the only well-funded tertiary education institution in the country that remains independent of controversial prime minister Victor Orbán.

Expressing “deep concern” at the new act, the group said it was the latest step by Orbán “to close out democratic institutions in the country, including press, media and NGOs”. They added: “If [closure] should happen it would be a serious blot on the EU’s conscience to have permitted this act of the Orbán government to pass without response.” They called on the EU to investigate the legality of the legislation and its consequences for freedom of education.

Founded in 1991 by Soros, who continues to fund it, the CEU was intended to be a bastion of liberal thought and to promote the values of democracy and an open society. In recent years the two men have had a strained relationship as Orbán accumulated power and cracked down on opposition.

Speaking to the Guardian, Szirtes, who came to the UK as a refugee aged eight following the 1956 Hungarian uprising, said: “I organised this letter because of the symbolic importance of the CEU, not as organised opposition to Orbán, but because the university is a very important symbol of independence in Hungary.”

Noting the prime minister’s crackdown on the media, cultural institutions and NGOs deemed to oppose his right wing regime, the poet and translator added: “It was one independent place that was free of his financial pressures, so he couldn’t strangle it, and as such was the last bastion of hope against an authoritarian state in Hungary.”

The new law has been promoted as a “review” of some 28 foreign universities operating in the country, of which the CEU is the richest. Before the law was passed, education secretary Laszlo Palkovics was quoted by the BBC saying that the government supported the CEU. “This is not an anti-CEU investigation and not against Mr Soros,” he told the broadcaster.

In Hungary, students took to the streets after president János Áder signed the new act, which requires that the CEU can only remain open if an intergovernmental agreement between US president Donald Trump and Orbán is signed and a branch of the CEU opened in the US by February 2018. Because the other 27 foreign universities already have US campuses, the CEU is the only one that faces closure.

The CEU has launched a social media campaign, #IstandwithCEU, against the law. In a statement on the university website , it said it would seek legal remedies to fight the legislation, which it believes contradict Hungary’s Basic Law, which guarantees freedom of academic research, studies and education, as well as prohibits discrimination.

Soros, the Hungarian Embassy and the CEU had yet to respond to attempts to contact them.

Text of the letter: call for action from 400 international writers, artists, academics and professionals