"It's another crime that will lead to more retaliation," Shaath told AFP on a visit to New Delhi.

"Assassination leads to retaliation," Shaath said, adding that as Israel did not have the death penalty, killing a suspect without trial was "unacceptable".

Four Israeli missiles ploughed into the car in central Gaza Saturday, killing Abdullah Akel and Farid Mayat, both members of Ezzedine al-Qassam Brigades, the armed wing of the militant Palestinian movement Hamas.

The attack came hours after Israeli officials vowed to pursue Hamas through incursions and targeted assassinations to put an end to the group's firing of its homemade Qassam rockets at Israeli targets.

Reuters adds: An Israeli army helicopter fired several missiles at a car in the Gaza Strip on Saturday, killing two Hamas militants in the latest violence battering a US-backed peace initiative.

Palestinian Information Minister Nabil Amr said the attack in the Bureij refugee camp destroyed any chance for the resumption of talks with Israel and called on the United States to interfere and halt the cycle of violence.

In a separate Gaza incident, an eight-year-old Palestinian girl was killed by an Israeli tank shell while riding her bike near her home in Khan Younis, a town adjacent to a Jewish settlement, Palestinian security sources and medics said.

The army said troops opened fire in the area after an explosive device was detonated near an army patrol, damaging a military vehicle. An army spokesman said he could not confirm that anyone was hit.

Palestinian security officials said Abdullah Aqel, the leader of the Islamic group's military Izz el-Deen al-Qassam Brigades in central Gaza, was killed in Saturday's missile strike in Gaza along with Brigades member Farid Mayet.