Israel bombarded as many as 80 locations in the narrow Gaza enclave, flattening Gaza's police headquarters and taking the Palestinian death toll to nearly 100 in six days of onslaught.
As civilian casualties mounted in Gaza, Egypt intensified efforts to mediate a truce between the two sides, and UN chief Ban Ki-moon called for an immediate ceasefire as he prepared to join truce talks in Cairo.
The death toll in the coastal territory since the Operation Pillar of Defense began had reached 95, one third of the killed were not involved in the conflict, according to Israel's Haretz newspaper.
It said the Israel Defence Forces (IDF) admitted that nine Palestinians were killed "accidentally" in a missile strike in which a top operative in Hamas rocket programme was hit.
The army's chief military spokesman, Yoav Mordechai, told Israel's Channel 2 TV that the intended target of the strike had been Yehiya Rabiah, the head of Hamas's rocket-launching unit, but that there had been "civilian casualties".
While Israeli military continued to pound the narrow Gaza Strip -- 41 km long, 6-12 km wide -- incessantly from both land and sea, it also prepared for a ground offensive in case truce talks failed.
Even as casualties mounted, including women and children, Israel's prime minister, Benjamin Netanyahu said he had assured world leaders that Israel was doing its utmost to avoid causing civilian casualties.
Ban on the other hand expressed concern at the increasing violence in a statement before setting off for the region.
"I am deeply saddened by the reported deaths of more than ten members of the Dalu family... (and) by the continuing firing of rockets against Israeli towns, which have killed several Israeli civilians," Ban said.
Sunday turned out to be the bloodiest day in the conflict, with 29 Palestinians reported killed. Among the dead was a family of at least nine people - half of them children - killed when an Israeli airstrike demolished a three-storey building in Gaza, according to Al Jazeera.
Meanwhile, Egyptian President Mohamed Mursi met Hamas's political leader Khaled Meshaal, and Ramadan Shallah of Islamic Jihad as part of the mediation efforts. Israeli negotiators had also arrived in Cairo for talks yesterday.
While most Western nations have supported Israel's military onslaught calling it the country's right to self defence, some leaders spoke against the rising civilian casualties in Gaza.
Turkish Prime Minister Recep Tayyip Erdogan accused Israel of committing "terrorist acts" in Gaza, and charged the West of turning a blind eye to the killings of civilians there.
"Those who equate Islam with terrorism condone mass murder of Muslims and turn their heads against the killing of children in Gaza," he said at the Eurasian Islamic Council conference in Istanbul.
"For this reason I say that Israel is a terrorist state and that its acts are terrorist acts," he said.
Meanwhile, the leaders of the Palestinian movements of Fatah, Hamas and Islamic Jihad in the West Bank today pledged unity and vowed to "end the division" in solidarity with Palestinians in the Gaza Strip.
German Foreign Minister Guido Westerwelle, who is scheduled to travel to the region, also called for creating conditions for ceasefire.
US Secretary of State Hillary Clinton emphasised Israel's right to "self-defence", but spoke to several world leaders, asking them to use their influence to work for an immediate de-escalation of tensions.
The Israeli army said it had fired missiles at more than 1,300 locations in Gaza since Wednesday, and that 544 rockets were fired back against Israel. Three Israelis have been killed and a few dozen wounded.
The rocket strikes into Israeli territory saw a lull, a day after 75 rockets were fired into southern Israel, a substantial drop from the weekend in which as many as 230 rockets were fired daily.