Former Pakistan prime minister Imran Khan has termed the attempted murder of Salman Rushdie as terrible and sad, indicating that while the anger in the Islamic world at the Mumbai-born author's controversial novel The Satanic Verses was understandable, the act was unjustifiable, a media report said on Friday.

Rushdie, 75, was stabbed by a 24-year-old New Jersey resident identified as Hadi Matar, a US national of Lebanese origin, on stage last week while he was being introduced at a literary event of the Chautauqua Institution in Western New York.

He suffered three stab wounds to his neck, four stab wounds to his stomach, puncture wounds to his right eye and chest, and a laceration on his right thigh, Chautauqua County District Attorney Jason Schmidt said during the suspect's arraignment.

"I think it's terrible, sad," Khan said in an interview to the Guardian newspaper, when asked for his response on Rushdie's assault.

Rushdie understood, because he came from a Muslim family. He knows the love, respect, reverence of a prophet that lives in our hearts. He knew that, Khan told the British newspaper.

"So, the anger I understood, but you can't justify what happened," he explained.

Khan and Rushdie share an acrimonious relationship.

In 2012, the Pakistan Tehreek-e-Insaf chairman had refused to attend a media conclave in New Delhi after he learnt about Rushdie's participation.

Khan cancelled his participation as a keynote speaker at the conclave stating that he could not think of participating in an event that included Rushdie, who has caused "immeasurable hurt to Muslims across the globe".

Rushdie's fourth book The Satanic Verses, released in 1988, forced him into hiding for nine years.

The late Iranian leader Ayatollah Ruhollah Khomeini accused Rushdie of blasphemy over the book and in 1989 issued a fatwa against him, calling for his death.

Rushdie's writing has led to death threats from Iran, which has offered a USD 3 million reward for anyone who kills him.