Syria's regime on Sunday slammed as "hostile" a French decision to host an opposition ambassador, as its forces bombarded southern districts of the capital and clashes raged nationwide.

France on Saturday invited the National Coalition, the newly formed Syrian opposition bloc, to send an envoy to Paris, after President Francois Hollande met its leader, Ahmed Moaz al-Khatib.

Palestinian President Mahmoud Abbas called on Sunday for Palestinians to stage peaceful demonstrations against Israel's military offensive on Gaza militant groups.

"I call on the Palestinian people to intensify their peaceful demonstrations in the streets against the Israeli aggression in Gaza," he said at a meeting with the Palestinian leadership.

Khalil al-Dallu screams. "They said Mohammed was alive!" he shouts as emergency workers pull the body of a young man from a Gaza City home leveled by an Israeli strike on Sunday.

His face quickly crumples into tears as the emergency staff tell him that his cousin is in fact dead -- one of six members of the Dallu family killed when an Israeli missile struck the Nasser neighborhood, flattening the three-story building where they lived.

The Israeli government on Sunday admitted it had become the victim of a mass cyber-warfare campaign with millions of attempts to hack state websites since the start of its Gaza offensive four days ago.

Speaking ahead of the weekly cabinet meeting, Israeli Finance Minister Yuval Steinitz said the government was now waging war on "a second front -- of cyberattacks against Israel."

Russian Foreign Minister Sergei Lavrov will seek a meeting of the so-called Middle East quartet over the Gaza crisis when he holds talks with U.S. Secretary of State Hillary Clinton in Asia this week, the Russian news agency Ria Novosti said Sunday.

Russia has condemned as "disproportionate" the Israeli blitz on the impoverished Gaza Strip, where 64 Palestinians have been killed while three Israelis have been killed in rocket attacks by Palestinian militants since Wednesday.

An Israeli official landed in Cairo on Sunday for Egypt-mediated truce talks with Hamas to end the Gaza conflict, Egyptian security officials said.

The official landed in a small plane at 1100 GMT and was quickly escorted away by intelligence personnel, the security officials said.

The family of a Palestinian-Jordanian journalist missing in Syria for more than three months has appealed for help in securing his release, Beirut-based media rights watchdog SKeyes said on Sunday.

"Nasser al-Kadumi, brother of (U.S. broadcaster) Al-Hurra correspondent Bashar Fahmi al-Kadumi... called for the assistance of everyone able to help ensure his release," a statement said.

Israel's Foreign Minister Avigdor Lieberman said on Sunday that Israel would not negotiate a truce with Gaza Strip's Hamas rulers as long as rocket fire continues from the Palestinian enclave.

"The first and absolute condition for a truce is stopping all fire from Gaza," he said before meeting French Foreign Minister Laurent Fabius, adding that all militant factions in Gaza would have to commit to cease rocket fire.

U.S. President Barack Obama Sunday said it was "preferable" for the Gaza crisis to be ended without a "ramping up" of Israeli military action, as fears mounted of a new invasion of the Hamas-run territory.

"Israel has every right to expect that it does not have missiles fired into its territory," Obama said, adding, "if that can be accomplished without a ramping up of military activity in Gaza, that is preferable".

The Gaza-based offices of a Kremlin-funded international Russian TV broadcaster were severely damaged Sunday in an Israeli raid on two buildings housing Palestinian and other media outlets, the station said.

The Israeli army confirmed attacking the Shurouq center in Gaza City in an attempt to interrupt what it said was Hamas "operational communications" from the building.