GAZA CITY, Palestinian Territories (AFP) ― Israel said Sunday it would further expand its ground offensive in Gaza as the death toll from its intensive assault soared to 364 ahead of a visit to the region by U.N. chief Ban Ki-moon.

Islamist movement Hamas, the main power in Gaza, refused to yield in the face of the relentless air, sea and land attacks, continuing its own assaults and reiterating that its demands must be met for any cease-fire to take place.

Diplomatic efforts to seek a truce were set to intensify Sunday with the arrival of Ban in the region to help Israelis and Palestinians “end the violence and find a way forward.”

Meanwhile Hamas chief Khaled Meshaal was to meet Palestinian president Mahmud Abbas in Qatar to discuss an Egyptian-proposed truce, and the movement said it had received an invite to Cairo for cease-fire talks.

On day 13 of the bloodiest Gaza conflict in several years, early morning Israeli bombardments killed 14 people, medics said, including the son of a senior Hamas official.

Sunday’s deaths raised the total toll to 357 Palestinians.

Seven Israelis have been killed, including two soldiers in a Saturday commando-style raid inside Israeli territory by Hamas militants.

Two other soldiers were killed on Saturday, one by an antitank missile and the other in a firefight with a militant who had emerged from a tunnel and attacked troops, the army said Sunday.

Israel said its ground operation to stamp out militant cross-border rocket fire, which began Thursday, was set to “expand” later Sunday.

“This evening, the ground phase of Operation Protective Edge expands, as additional forces join the effort to combat terror in the Gaza Strip and establish a reality in which Israeli residents can live in safety and security,” the army said in a statement.

The Jewish state has authorised the call-up of more than 53,000 reserve troops.

An intensive artillery barrage east of Gaza City before dawn Sunday killed two children, medics said, adding to a high civilian death toll.

The increasing number of children killed in the conflict is causing a growing outcry, with a joint statement from NGOs War Child and Defense for Children International saying more children had been killed than militants. 

Figures provided by the U.N. children’s agency, UNICEF, indicate at least 73 of the victims were under the age of 18.

Israel’s Prime Minister Benjamin Netanyahu absolved Israel of all responsibility Saturday for civilian casualties, laying the blame squarely on the shoulders of Hamas.

A statement from Netanyahu’s office cited him as saying Hamas was “using innocent civilians as human shields for its terrorist activities; it is responsible if civilians are inadvertently hit.”

The U.N.’s Palestinian refugee agency, UNRWA, said earlier in the week it found 20 rockets stored in one of its schools in Gaza, condemning the “group or groups” involved.

UNRWA has opened 49 of its schools to shelter those fleeing the most heavily-bombarded areas.

So far, more than 60,000 Gazans have sought sanctuary at U.N. institutions, the agency said.

Hamas “received an invitation, through mediators, for a delegation headed by Khaled Meshaal to visit Cairo and discuss the Egyptian initiative,” it said in a statement.

It said the Islamist movement said its “position on the initiative is known, but it is at the same time ready to cooperate” should its demands for a truce be met.

An Egyptian Foreign Ministry official said he could not confirm or deny the new invitation.

Hamas earlier in the week rejected Egypt’s proposal for a truce ― which was accepted by Israel ― saying that it had not been consulted.

Hamas relations with Egypt have hit a low since Cairo’s military regime took power last July, ousting Hamas ally the Muslim Brotherhood.

Turkey and Qatar, where Meshaal is based, are more sympathetic to the movement.

Abbas and Meshaal will meet in Qatar on Sunday to discuss the Egyptian-proposed truce, an official close to Abbas said.

Hamas spokesman Fawzi Barhum said his movement had presented its demands to “all parties concerned, including Qatar, Turkey and the Arab League” as well as Abbas and Egypt.

The demands include a complete lift of the siege on Gaza, opening the Rafah crossing with Egypt and freedom of movement in the border areas.

In addition, Hamas demands the release of its members who had been freed in a 2011 deal and recently rearrested in an Israeli crackdown on the West Bank.