Daughters of the American tourist killed when Palestinian terrorists hijacked a cruise ship in 1985 have expressed outrage at the early release of one of his killers after more than 23 years in jail.

Youssef Magied al-Molqui has been transferred from prison in Palermo, Sicily, to a holding centre for immigrants in nearby Trapani while officials work to expel him.

Al-Molqui was sentenced to 30 years for his part in the hijack of the Achille Lauro off the Egyptian coast. He shot Leon Klinghoffer, an elderly Jewish man from New York, and ordered him to be dumped in the sea while still in his wheelchair.

Mr Klinghoffer’s daughters, Lisa and Ilsa, said: “We are outraged at the news of the release of Youssef Magied Al-Molqui for good behaviour.

“There should be no good behaviour clause for terrorist murderers,” they said. “This is a travesty.”

Italy customarily reduces inmates’ sentences, often by several years, for model behaviour in prison.

In 1996, al-Molqui was granted a 12-day leave from prison and failed to return. He was recaptured in Spain after three weeks on the run. He may fight Italy’s decision to expel him as he has married an Italian woman and has no other recognised citizenship.

Another convicted Achille Lauro hijacker, Ibrahim Fatayer Abdelatif, was released last year. Italian authorities have tried to expel him, but his lawyers have appealed the decision, arguing he should be allowed to stay for humanitarian reasons because he too has no citizenship.

The Leon and Marilyn Klinghoffer Memorial Foundation of the Anti-Defamation League works to combat the threat of terrorism through educational, political and legal means.

An opera about the hijack, The Killing of Klinghoffer, by composer John Adams, caused controversy when it was written in 1991.