A GROUP of 150 writers, academics and activists have signed an open letter warning against the “restriction of debate”.

The signatories, who include JK Rowling, Salman Rushdie and Margaret Atwood, came together to denounce “a vogue for public shaming and ostracism” and a “blinding moral certainty” in moral society.

Several of those to sign the open letter have been criticised for comments which caused offence – including Harry Potter author Rowling, whose views on transgender issues came under fire in recent weeks.

READ MORE: Harry Potter author JK Rowling criticised over ‘transphobic’ tweets

Others adding their voices to the warning, published in yesterday’s Harper’s Magazine, included intellectual Noam Chomsky, feminist Gloria Steinem, chess grandmaster Garry Kasparov and author Malcolm Gladwell.

The letter states: "The free exchange of information and ideas, the lifeblood of a liberal society, is daily becoming more constricted.

"We uphold the value of robust and even caustic counter-speech from all quarters.

"But it is now all too common to hear calls for swift and severe retribution in response to perceived transgressions of speech and thought."

It went on: "Editors are fired for running controversial pieces; books are withdrawn for alleged inauthenticity; journalists are barred from writing on certain topics; professors are investigated for quoting works of literature in class; a researcher is fired for circulating a peer-reviewed academic study; and the heads of organizations are ousted for what are sometimes just clumsy mistakes."

While the group praised a “needed reckoning” on racial justice seen in worldwide protests, they condemned “disproportionate punishments” from institutional leaders conducting “panicked damage control”.

READ MORE: This is why JK Rowling’s non-fiction foray caused a Twitter storm

The letter has sparked a fresh row over cancel culture, with one signatory already backtracking on their involvement.

Author and transgender activist Jennifer Finney Boylan tweeted: "I did not know who else had signed that letter.

"I thought I was endorsing a well-meaning, if vague, message against internet shaming."

She apologised for signing the letter, while historian Kerri Greenidge also said she did not endorse the message and has asked for a retraction.

Meanwhile, co-founder of liberal news site Vox, Matthew Yglesias, came under fire for signing from a colleague.

Emily VanDerWerff, a trans woman, said on Twitter that she had contacted the publication’s editors to tell them Yglesias’s involvement made her feel “less safe at Vox”.

Journalist and author Glenn Greenwald was also critical of the letter. He tweeted: “As is usually the case for people who manifest in favor of free and open debate and against repression, several of the people on this @Harpers Open Letter have behavior in their past that reflects the censorious mentality they’re condemning here.”