GAZA CITY ø Israel's military has killed a leading Hamas operative and the head of the Kassam missile project.

An Israeli aircraft fired two missiles that killed Adnan Al Ghoul in what was regarded as the most significant blow to Hamas in the Gaza Strip since April 2004. Al Ghoul, in his car when the attack took place on late Thursday in Gaza City, oversaw the effort to design and produce the Kassam-class, short-range missile.

Since 2002, about 500 Kassam missiles were fired toward Israeli communities.

Three versions of the Kassam have been developed, the most advanced of which was capable of a range of up to 14 kilometers.

"Since the beginning of the current conflict on September 2000, Al Ghoul was responsible for the manufacturing of the Hamas weaponry in the Gaza Strip," an Israeli military statement said. "He was among those responsible for developing and producing the Kassam-1 and the Kassam-2 rockets. In addition, he was working to produce new anti-tank and-anti aircraft weaponry."

Palestinian sources said Hamas was developing the so-called Kassam-4, with a range of about 20 kilometers. They said Al Ghoul had led the Kassam enhancement effort.

Al Ghoul, 46, has been sought by Israel since 1994. He was said to have also been responsible for suicide attacks that killed scores of Israelis.

In 1996, Al Ghoul, then a member of the Iranian-sponsored Islamic Jihad, was arrested by the Palestinian Authority and imprisoned. He later escaped and fled to Lebanon and Syria.

In Lebanon, Al Ghoul was said to have been trained in missile and rocket technology by Hizbullah and Iran. He infiltrated the Gaza Strip via the Mediterranean, joined Hamas and was said to have used his expertise for the development of Hamas's Kassam missile.

"He was an engineer with a very sharp mind for weaponry and rocket technology," a Palestinian source said.

Palestinian sources said Israel tried to assassinate Al Ghoul three times over the last four years. Al Ghoul's son, a PA security officer, was killed in 2001.

In Thursday's missile attack, Al Ghoul's aide and driver, Imad Abbas, was also killed. Abbas was also said to have played a leading role in the Kassam development and production project.

Palestinian sources said the killing of the Hamas operatives would not halt Hamas missile production. But they said Al Ghoul's death could hamper plans to enhance the missile.

Hours after the Israeli air strike, Hamas fired two Kassam missiles toward the Israeli city of Sderot. Palestinian gunners also fired 20 mortars against communities in the Gaza Strip on late Thursday and Friday.

The killing of Al Ghoul was regarded as the biggest blow to Hamas since April 2004. In March 2004, Hamas founder Ahmed Yassin was slain in an Israeli air attack, followed by the assassination of Yassin's successor, Abdul Aziz Rantisi, in April.