A general view shows burned cars after a rocket fired from Gaza landed in Ashdod October 29, 2011.[Photo/Agencies]

GAZA - Israel's air force bombed an Islamic Jihad base in the Hamas-governed Gaza Strip on Saturday, killing five senior militants and drawing cross-border Palestinian rocket salvoes that killed an Israeli civilian.

The flare-up smashed the relative lull in violence that had surrounded an Egyptian-mediated prisoner swap last week between the Jewish state and Islamist Hamas, which is negotiating a fraught power-share with its U.S.-backed Palestinian rivals.

The air strike on the training camp in southern Rafah followed a rocket launch this week which the Israelis blamed on Islamic Jihad. That attack caused no casualties but the rocket landed deep enough to set off sirens on Tel Aviv's outskirts.

Islamic Jihad said one of its commanders, Ahmed al-Sheikh Khalil, and four comrades who had overseen production of bombs and rockets for the faction died in the mid-day strike. Two other fighters were wounded.

Israel's military said its aircraft "targeted a terrorist squad ... that was preparing to launch long-range rockets".

It said in a statement that those hit were responsible for the rocket launch late on Wednesday, though no Palestinian faction had claimed responsibility.  

Islamic Jihad, a sometime Hamas ally that has recently chafed at its rule, vowed revenge, a call echoed by smaller Gaza groups.

"There is no chance of speaking about a truce now, following such a big crime against leaders of the group," said Islamic Jihad spokesman Abu Ahmed.

By evening, at least 20 rockets and mortar bombs hit southern Israel, killing a 50-year-old man in coastal Ashkelon and wounding two other civilians, police said.  

Islamic Jihad and the more secular factions Popular Front for the Liberation of Palestine (PFLP) and al-Aqsa Martyears Brigades separately took credit.

A Palestinian mourns at a hospital following an Israeli air strike in Rafah in the southern Gaza Strip October 29, 2011. [Photo/Agencies]

Consequences

Two more Israeli air strikes followed, killing four Islamic Jihad gunmen and wounding a fifth. The military said the gunmen had carried out cross-border shellings.

Israel demanded international intervention to stop the Palestinian attacks.

"We seek no confrontation with the Palestinians and do not want to inflame the situation, but we will not absorb shelling after shelling without a response," Foreign Minister Avigdor Lieberman said, threatening unspecified "consequences".

The United Nations, which runs an extensive aid network in Gaza and is among foreign powers trying to revive moribund peace talks between Israel and the U.S.-backed Palestinian administration in the occupied West Bank, appealed for calm.

"It is vital to de-escalate now, without delay," said senior U.N. envoy Robert Serry.

Hamas last week repatriated an Israeli soldier it seized in 2006 in exchange for the release of more than 1,000 jailed Palestinians. That deal, brokered by Egypt's military rulers, stirred speculation a more enduring detente was in the works.

Remarking on the Rafah deaths, Hamas spokesman Sami Abu Zuhri accused Israel of a "serious escalation against our people".

In keeping with Israeli government policy, the military statement said Hamas bore ultimate responsibility "for any terrorist activity emanating from the Gaza Strip".

Islamic Jihad released images of what it said was the firing by its men of a truck-mounted multiple rocket-launcher, a platform recalling those of Libyan rebels and not previously seen in Gaza. Israel says Gazan arsenals have been boosted by gun-running from Libya since the fall of its ruler, Muammar Gaddafi.