RAMALLAH, West Bank -- Aides to the Palestinian president said Sunday that he will soon appeal to the international community to set a deadline for Israel to end its occupation of lands captured in the 1967 Mideast war and make way for an independent Palestinian state.

President Mahmoud Abbas was expected to unveil his proposal as part of a "day after" plan following the current war in the Gaza Strip, likely at a meeting of the Palestinian leadership on Tuesday, said the aides, who spoke on condition of anonymity because the plan has not yet been made public.

Abbas is plotting his move even as the fighting continues to rage. Israel's prime minister, Benjamin Netanyahu, warned Sunday that the 7-week-old military campaign in Gaza would stretch into September -- despite growing anger among residents in southern Israel over the military's inability to halt rocket and mortar fire out of the Palestinian territory following the death of a 4-year-old Israeli boy over the weekend.

In new fighting Sunday, the Israeli air force flattened a seven-floor office building and severely damaged a shopping centre in southern Gaza, signalling a new escalation.

Palestinian officials said 13 people were killed in Israeli airstrikes, bringing the death toll to more than 2,100 Palestinians since fighting erupted on July 8. Sixty-eight Israelis have also died, all but four of them soldiers.

With no end in sight to the fighting, Abbas has been searching for ways to assert himself on the international stage. He is seeking a foothold back in Gaza, which was captured from his forces by Hamas seven years ago, and is eager to show the Palestinian public he is working to end the fighting and lead the Palestinians to independence.

One official said that Abbas has grown disillusioned after two decades of failed efforts to reach a negotiated peace settlement with Israel. He said the Palestinians want a "fixed date" for an Israeli withdrawal from lands claimed by the Palestinians and a timetable for establishing a Palestinian state.

In an interview on Egyptian television over the weekend, Abbas said he would soon present his plans to Arab, American and European leaders.

"It is an unconventional solution, but I will not declare a war on Israel. It is a political and diplomatic solution," he said.

He declined to elaborate, saying only that he would tell the United Nations in an address next month that the Palestinians want independence immediately. "Otherwise, this opportunity will be lost forever," he said.

An aide to Abbas said the plan would include an appeal to the Security Council, whose resolutions are legally binding, to call for an end to Israel's occupation of lands captured in the 1967 Mideast war.

The Palestinians seek the West Bank, east Jerusalem and Gaza for their state. Israel captured all three areas in 1967, though it withdrew from Gaza in 2005.

With Israel opposed to a withdrawal to its pre-1967 lines, it will likely seek U.S. help in thwarting the bid. The U.S. has historically vetoed Security Council resolutions seen as unfavourable to Israel.

The Palestinian official said that if this happens, the Palestinians will then begin the process of joining the International Criminal Court, where they could pursue war crimes charges against Israel.

The Palestinians were accepted as a nonmember state by the UN General Assembly in 2012, a status that allows them to join international bodies, including the International Criminal Court. Israeli officials see a Palestinian bid to join the court as a hostile act -- as well as a serious threat.

Israel strongly opposes Palestinian attempts to pursue independence at the United Nations, saying it is an attempt to circumvent the negotiating process. Netanyahu's office declined comment on the latest Palestinian plans, saying it wanted to receive details officially.

Speaking to his Cabinet Sunday, Netanyahu said the public must show patience and warned the operation could go into September.

"I said on the first day of the operation that it could take time and we are prepared that this campaign might continue even after the start of the school year," he said.

While the Israeli public has widely supported the campaign to halt rocket attacks out of Gaza, the government has come under criticism for its inability to stop the fire.

There was widespread anger following the death of 4-year-old Daniel Tragerman, who was killed in a Palestinian mortar attack Friday. Hundreds of people attended the boy's funeral Sunday.

"In a second, it was over. We lost you, and we are left with horrific images that will accompany us our entire lives," the boy's mother, Gila, said in a eulogy.

During the fighting, Israel's air raid warnings and rocket-defence system have largely protected the population from incoming rockets. But the system is unable to protect against mortar fire, which is fired from short range, giving little warning for people to run for cover.

"Why was it necessary to wait for a 4-year-old to be killed to turn the war against the mortar shells into a main goal?" Alex Fishman, a commentator on military affairs, wrote in the Yediot Ahronot daily. "After all, from the outset it was obvious that the fatal weapon in this war was not the rockets, but the mortar shells, against which there is no effective warning."

The Gaza war stems from the kidnapping and killing of three Israeli teens in the West Bank by Hamas operatives in June, which triggered a massive Israeli arrest campaign in the West Bank, followed by an increase in rocket fire from Gaza.

Since the fighting began, Israel has launched some 5,000 airstrikes at Gaza, while Gaza militants have fired close to 4,000 rockets and mortars, according to the Israeli military.

Israel says it is targeting sites linked to militants, including rocket launchers, command centres and weapons depots. The UN says about three-fourths of the Palestinians killed have been civilians.

Barzak reported from Gaza City, Gaza Strip. Ian Deitch in Jerusalem contributed reporting.