Prime Minister Boris Johnson says he is "appalled" at the attack which has left author Salmon Rushdie in hospital.

The PM was reacting after Rushdie, 75, was stabbed while being introduced at a speaking event in New York State, in the US.

It came after the writer endured decades of threats to his life, after a 'fatwa' was issued calling for his assassination after the release of his controversial work, The Satanic Verses, in 1988.

He was attacked, apparently by a member of the audience, as he was preparing to give a lecture on stage at the Chautauqua Institution on Friday.

Mr Johnson reacted to the news in a tweet, saying: "Appalled that Sir Salman Rushdie has been stabbed while exercising a right we should never cease to defend.

"Right now my thoughts are with his loved ones. We are all hoping he is okay."

Home Secretary Priti Patel also tweeted her reaction to the news.

"Shocked and appalled to hear of the unprovoked and senseless attack on Sir Salman Rushdie," she wrote.

"Freedom of expression is a value we hold dear and attempts to undermine it must not be tolerated. My thoughts are with Sir Salman and his family."

Attack on Salman Rushdie - what we know

New York State Police have confirmed they are investigating the attack, which happened at around 11am Eastern Pacific Time, about 4pm in the UK.

A police spokesperson said: "On August 12, 2022, at about 11am, a male suspect ran up onto the stage and attacked Rushdie and an interviewer.

"Rushdie suffered an apparent stab wound to the neck, and was transported by helicopter to an area hospital. His condition is not yet known.

"The interviewer suffered a minor head injury.

"A State Trooper assigned to the event immediately took the suspect into custody."

Boris Johnson, left, said he was 'appalled' at news Salman Rushdie had been attacked. Pictures: PAThe hall where Salman Rushdie was attacked. Picture: PA

The Chautauqua Institution, which was hosting Sir Salman Rushdie’s lecture when he was attacked, tweeted about the incident on Friday night.

It said: "We ask for your prayers for Salman Rushdie and Henry Reese, and patience as we fully focus on co-ordinating with police officials following a tragic incident at the Amphitheater today.

"All programs are canceled for the remainder of the day. Please consult the NYS Police statement."

READ MORE: Sir Salman Rushdie stabbed at New York State lecture

Why was a fatwa issued against Salman Rushdie?

Sir Salman’s book The Satanic Verses has been banned in Iran since 1988, as many Muslims consider it to be blasphemous.

A year later, Iran’s late leader Ayatollah Ruhollah Khomeini issued a fatwa, or edict, calling for Sir Salman’s death.

It is understood a reward of $3 million has been offered for his assassination.