Israeli police have arrested a group of Jewish extremists in connection with the kidnap and murder of a Palestinian teenager who was burned to death in a suspected revenge killing.

The brutal murder on July 2 triggered four days ofviolent clashes which began in east Jerusalem and have spread to more than half a dozen Arab towns in Israel, with hordes of angry protesters hurling stones at riot police.

The Shin Bet internal security agency said the suspects were arrested yesterday. Other details of the case were subjected to a strict gag order.

The arrests followed days of growing suspicion that Wednesday's murder was carried out by extremist Jews in revenge for last month's abduction and murder of three Israeli teenagers in the occupied West Bank.

Tensions rose in the south Sunday with Gaza militants firing another 17 rockets and projectiles over the border, after a night of 10 air strikes. No causality was reported.

Overnight, Israel police arrested 35 people.

The grisly murder has sparked shock, disgust and an outpouring of condemnation from both Israeli and Palestinian leaders.

Palestinian president Mahmud Abbas said he had asked UN Secretary General Ban Ki-moon to form "an international investigative committee on the terrorist crimes committed against the Palestinian people" by Israel, including Abu Khder's murder.