The man accused of stabbing Salman Rushdie at a literary event pleaded not guilty to attempted murder charges on Saturday, as the severely injured author appeared to show signs of improvement in hospital.

Hadi Matar, 24, was arraigned in court in New York state, with prosecutors outlining how Rushdie had been stabbed approximately 10 times in what they described as a planned, premeditated assault.

After the on-stage attack on Friday, Rushdie had been helicoptered to hospital and underwent emergency surgery.

His agent Andrew Wylie had said the writer was on a ventilator and in danger of losing an eye, but in an update on Saturday he told the New York Times that Rushdie had started to talk again, suggesting his condition had improved.

Author of The Satanic Verses and Midnight's Children, Rushdie had lived in hiding for years after Iran's first supreme leader Ayatollah Ruhollah Khomeini ordered his killing.

Read: Iranian media outlets add $0.6m to bounty for killing Salman Rushdie

US President Joe Biden on Saturday called it a “vicious” attack and offered prayers for Rushdie's recovery.

“Salman Rushdie — with his insight into humanity, with his unmatched sense for story, with his refusal to be intimidated or silenced — stands for essential, universal ideals. Truth. Courage. Resilience,” Biden said in a statement.

Matar is being held without bail and has been formally charged with second-degree attempted murder and assault with a weapon. Police provided no information on his background or what might have motivated him.

Effective death sentence

The 75-year-old novelist had been living under an effective death sentence since 1989 when Iran's then-supreme leader Khomeini issued a fatwa ordering Muslims to kill the writer.

The fatwa followed the publication of the novel The Satanic Verses which enraged some Muslims who said it was blasphemous.

In a recent interview with Germany's Stern magazine, Rushdie spoke of how, after so many years living with death threats, his life was “getting back to normal”.

“For whatever it was, eight or nine years, it was quite serious,” he told a Stern correspondent in New York. “But ever since I've been living in America, since the year 2000, really there hasn't been a problem in all that time.”

Rushdie moved to New York in the early 2000s and became a US citizen in 2016. Despite the continued threat to his life, he was increasingly seen in public — often without noticeable security.

Security was not particularly tight at Friday's event at the Chautauqua Institution, which hosts arts programmes in a tranquil lakeside community near Buffalo.

Witnesses said Rushdie was seated on stage and preparing to speak when Matar sprang up from the audience and managed to stab him before being wrestled to the ground by staff and other spectators.

Matar's family appears to come from the village of Yaroun in southern Lebanon, though he was born in the United States, according to a Lebanese official.

An AFP reporter who visited the village on Saturday was told that Matar's parents were divorced and his father — a shepherd — still lived there.

Journalists who approached his father's home were turned away.

Matar was “born and raised in the US,” the head of the local municipality, Ali Qassem Tahfa, told AFP.