Occupied Jerusalem: Israel's Mossad secret service agency killed a Palestinian wanted for airplane hijackings by feeding him poisoned Belgian chocolate over six months in the late 1970s, the author of a new book said on Saturday.

The book, Striking Back, is apparently the first time that details of the killing have come to light and provides a glimpse at how sophisticated Israel is at poisoning.

In his book, author Aaron Klein describes how Israel tracked down Wadia Haddad, an operative of the Popular Front for the Liberation of Palestine(PFLP), in Baghdad.

Suspected in multiple hijackings, including the 1976 takeover of an Air France airplane in Entebbe, Uganda, Haddad knew from the Israeli tactics that he could be shot or bombed as he walked the street or picked up a phone.

Haddad was cautious of his every move, avoiding travel outside of Iraq, said Klein, a Time magazine correspondent in Jerusalem. But the 140-kg food lover had a weakness: chocolate.

In Baghdad of 1977, luxuries like fine chocolates were rare. Through a Palestinian working with Mossad who had got close to Haddad, the agency was able to feed Haddad chocolate brought from Belgium and spread with poison over six months, Klein said.

Haddad died in March 1978, showing only symptoms of leukemia but no signs of poisoning, Klein told the radio.