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.

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".

An Arab League delegation headed by the bloc's chief Nabil al-Arabi will visit Gaza on Tuesday in a show of support for the territory in the face of Israeli air strikes, a league official said.

"The Arab ministerial delegation formed by the Arab foreign ministerial council will visit Gaza on Tuesday, headed by Nabil al-Arabi," the official said in a statement .

A ground invasion of the Gaza Strip would lose Israel much international sympathy and support, British Foreign Secretary William Hague warned Sunday.

Hague told Sky News television it was much more difficult to limit civilian casualties in a ground assault and it would threaten to prolong the conflict.

Prime Minister Benjamin Netanyahu said on Sunday that Israel is ready to "significantly expand" its operation against militants in the Hamas-run Gaza Strip as it entered its fifth day.

"The army is prepared to significantly expand the operation," Netanyahu said at the start of the weekly cabinet meeting. "The soldiers are ready for any activity that could take place."

Talks on the possibility of a truce to end five days of violence in and around Gaza are under way, and a deal could be reached "today or tomorrow," a Palestinian official told Agence France Presse on Sunday.

"There are serious talks to reach a truce, and it is possible that understandings will be reached today or tomorrow," the senior official said.

Jordan's King Abdullah II called for an immediate halt to Israeli "aggression" against Gaza as he received Middle East Quartet envoy Tony Blair on Sunday, the royal palace said.

The monarch stressed "the need to speed up regional and international efforts to bring an immediate halt to Israeli aggression and military escalation," it said in a statement.

Israeli air strikes on Sunday killed 26 Palestinians in the bloodiest day so far of its massive air campaign on the Gaza Strip, as diplomatic efforts to broker a truce intensified.

With Egypt at the center of efforts to broker a ceasefire, Palestinian officials said it was possible a deal would be reached "today or tomorrow."

Egyptian President Mohammed Morsi called on his Argentine counterpart Cristina Kirchner to rally other Latin American leaders in support of stopping the violence in Gaza, Argentina said Saturday.

"The president of the Arab Republic of Egypt, Mohammed Morsi, contacted President Cristina Fernandez de Kirchner, to ask for her intervention, and through her the leaders of the region and the world, for an end of violence between Israel and the Palestinian faction Hamas, which rules the Gaza Strip," the government said in a statement on its website.

Arab League chief Nabil al-Arabi will head a delegation to Gaza in a show of solidarity after Arab ministers decided on Saturday to review their diplomacy towards Israel and show their support for the Palestinians.

The delegation will travel to Gaza "to affirm solidarity with the Palestinians," a League statement said after the foreign ministers' meeting. Arabi told reporters it would head for the enclave either on Sunday or Monday.