By Nidal al-Mughrabi, Dan Williams and Yusri Mohamed

GAZA/JERUSALEM/ISMAILIA, Egypt (Reuters) -Diplomatic efforts failed to get aid to the besieged Gaza Strip on Monday, and Israel ordered the evacuation of its villages in a strip of territory near its border with Lebanon, raising fears the war could spread to a new front.

Israel has vowed to annihilate the Hamas movement that rules Gaza, after Hamas fighters burst across the barrier to Israel on Oct. 7, gunning down 1,300 Israelis, mainly civilians, in the deadliest day in Israel's 75-year-old history.

It has put Gaza, home to 2.3 million Palestinians, under a total blockade and pounded it with unprecedented air strikes, and is widely expected to launch a ground assault. Gaza authorities say more than 2,800 people have been killed there, around a quarter of them children, and more than 10,000 wounded are in hospitals desperately short of supplies.

According to the United Nations, a million Gazans have already been driven from their homes. Power is out, sanitary water is scarce, and the last fuel for hospital emergency generators could be used up within a day.

Residents said overnight air strikes were the heaviest yet, and the bombing carried on through the day.

"We were inside the house when we found bodies scattering, flying in the air - bodies of children who have nothing to do with the war," said resident Abed Rabayaa, whose neighbour's house in Khan Younis, the main city in the southern part of the enclave, was hit overnight.

In the biggest sign yet that the war could spread to a new front, Israel ordered the evacuation on Monday of 28 villages in a two km- (1.2 mile-)deep zone near the Lebanese border. Lebanon's Hezbollah movement said it had targeted five Israeli positions.

Clashes this last week have been the deadliest in the Lebanon border area since a 2006 war between Israel and Hezbollah, which, like Hamas, is an ally of Iran.

In a speech to parliament, Prime Minister Benjamin Netanyahu said Israelis should prepare for a long battle.

"Now we are focused on one target: to unite forces and charge forward to victory. This requires determination because victory will take time," he said.

"And I have a message for Iran and Hezbollah, don't test us in the north. Don't make the same mistake you once made. Because today the price you will pay will be much heavier."

'SHELLING, CRYING, SCREAMING, BLOOD'

The 10 days of strikes so far have failed to eliminate Hamas' capacity to fire rockets into Israel, where warning sirens sounded. Hamas said it fired a barrage at Jerusalem and Tel Aviv.

During one alert, Netanyahu and U.S. Secretary of State Antony Blinken - visiting Israel for the second time in five days - briefly sheltered together in a bunker.

Diplomatic efforts have concentrated on getting aid into Gaza through the Rafah crossing with Egypt, the sole route out that is not controlled by Israel. The Egyptian side of the crossing was deserted on Monday, with trucks loaded with supplies waiting at the nearby town of Al-Arish.

Cairo said the Rafah crossing was not officially closed but was inoperable due to Israeli strikes on the Gaza side.

"We are waiting for the green light for the aid to enter and dozens of volunteers are ready at any time," a Red Crescent official in northern Sinai said.

Early on Monday two Egyptian security sources had told Reuters a ceasefire for several hours in southern Gaza had been agreed for aid and evacuations at Rafah. However, Egyptian state TV later quoted an unnamed, high-level source as saying no such truce had been agreed, and Israel and Hamas also both denied it.

"There is an urgent need to alleviate the suffering of Palestinian civilians in Gaza," Egyptian Foreign Minister Sameh Shoukry told reporters, adding talks with Israel on opening Rafah for aid had so far been fruitless.

U.N. humanitarian aid chief Martin Griffiths was travelling to Cairo on Tuesday to try to get supplies through. "It is critical that life-saving assistance is allowed to move through the Rafah crossing without delay," his office said.

Washington has been focusing on getting the crossing briefly opened to allow some of the few hundred Gazans with U.S. passports to leave. Shoukry said Egypt could allow medical evacuations and let some Gazans cross with permission to travel.

But there has been no public talk of Egypt accepting a mass influx of refugees, meaning the vast majority of Gazans are unlikely to be offered a route out. Egypt and other Arab states say a mass exodus would be unacceptable, amounting to the expulsion of Palestinians from their land.

Those trying to reach the crossing inside Gaza described the route as perilous and under Israeli attack.

"On our way to the crossing they shelled Rafah Street and we started screaming," said one resident near the crossing, Hadeel Abu Dahoud. "Nowhere is safe in Gaza. Wherever we go there's shelling, shelling, crying, screaming, blood."

Israel has said more than a million people in the northern half of the enclave must head to the southern half for their safety even though Hamas has told them to stay put. While tens of thousands have complied and fled, the United Nations says there is no way to move so many people without causing a humanitarian catastrophe.

With each day of air strikes, Gazans have been clawing at the rubble of flattened buildings with bare hands to rescue neighbours and recover the dead, with virtually no mechanical equipment to clear away the wreckage.

Civil emergency officer Abid Saqir told Reuters at one bomb site that there were at least 1,000 bodies trapped under rubble at locations across the enclave.

Mohammad Abu Saleema, director of the Shifa hospital, the Gaza Strip's biggest, said seriously wounded patients must be sent to hospitals outside Gaza or there would be no room for more to be treated.

Medics said they will have to switch off lifesaving hospital equipment if they run out of fuel for hospital generators.

"If the hospital stops working, the whole world will be responsible for the lives of hundreds and thousands of patients who rely on our services, especially from Shifa," said Ashraf Al-Qidra, a Gaza health ministry official.

(Reporting by Nidal al-Mughrabi, Bassam Massoud and Nuha Sharaf in Gaza, Ari Rabinovitch, Dan Williams, Henriette Chacar, Dedi Hayun, Maayan Lubell, Emily Rose, James Mackenzie and John Davison in Jerusalem, Parisa Hafezi in Dubai, Humeyra Pamuk, Hatem Maher, Ahmed Tolba and Omar Abdel-Razek in Cairo, Nandita Bose, Rami Ayyub and Katharine Jackson in Washington, Michelle Nichols at the United NationsWriting by Angus MacSwan and Peter GraffEditing by Philippa Fletcher, Hugh Lawson and Howard Goller)

Reuters

Talks fail to let aid reach Gaza; Israel evacuates Lebanon border