Italian Prime Minister Mario Monti and his Qatari counterpart urged an immediate ceasefire in Gaza on Monday, as Israel and militants in the Palestinian enclave traded fire for a sixth straight day.

"We are very worried about the escalating violence," Monti said at a joint news conference in Doha with Qatari Prime Minister Sheikh Hamad bin Jassem al-Thani.

"A ceasefire must quickly be reached to allow the peace process to begin as soon as possible," he told reporters according to an official translation.

The Qatari prime minister described the events in the Gaza Strip as "unacceptable" and echoed his counterpart by calling both sides to commit to a ceasefire.

"We are for a return of calm. But this must happen clearly and no side must be allowed to continue to assassinate or initiate side battles," said Sheikh Hamad. "A truce must be observed from both sides."

Israel launched its Gaza operation on Wednesday by killing a top Hamas military commander in an air strike, and Palestinian militants responded with rocket fire.

As fighting continued on Monday, ceasefire efforts gathered steam, with senior Hamas officials in Cairo saying Egyptian-led talks on Sunday with Israel were "positive" but now focused on the need to guarantee the terms of any truce.

Monti said his government was in contact with "Egyptian President Mohamed Morsi, Israeli Prime Minister Benjamin Netanyahu, the Palestinian Authority, as well as Qatar's emir and its prime minister".

Meanwhile the Gaza death toll reached 95 in the worst Israeli-Palestinian violence in four years. Three Israelis have been killed and more than 50 injured by rocket fire since Wednesday.

The Qatari premier also called for "lifting the oppressive blockade on Gaza."

In October, Qatar's emir was the first head of state to visit Gaza since the Palestinian Islamist group Hamas seized it from forces loyal to Palestinian President Mahmud Abbas in 2007.