Israel said it is prepared to fight for months or longer to defeat Gaza's Hamas rulers, as its ground offense intensifies with more airstrikes and artillery fire.

Qatar, which has played a key mediating role, says efforts to stop the war and have all hostages released will continue, but a willingness to discuss a cease-fire is fading.

A British Palestinian surgeon who spent weeks in the Gaza Strip during the current Israel-Hamas war as part of a Doctors Without Borders medical team said he has given testimony to a British war crimes investigation unit.

Ghassan Abu Sitta, a plastic surgeon specializing in conflict medicine, has volunteered with medical teams in multiple conflicts in Gaza, beginning as a medical student in the late 1980s during the the first Palestinian uprising. He has also worked in other conflict zones, including in Iraq, Syria and Yemen.

Yemen's Iran-backed Huthi rebels have threatened to attack any vessels heading to Israeli ports unless food and medicine were allowed into the besieged Gaza Strip.

The latest warning comes amid heightened tensions in the Red Sea and surrounding waters following a series of maritime attacks by Houthi rebels since the start of the Israel-Hamas war on October 7.

Mediation efforts are continuing to secure a new Gaza ceasefire and free more hostages held by Hamas despite ongoing Israeli bombardment that is "narrowing the window" for a successful outcome, Qatar's prime minister said Sunday.

Heavy fighting raged overnight and into Sunday in the southern Gaza town of Khan Younis, as Israel pressed ahead with its offensive after the U.S. blocked the latest international efforts to halt the fighting and rushed more munitions to its close ally.

Israel has faced rising international outrage and calls for a cease-fire after the killing of thousands of Palestinian civilians and the displacement of nearly 85% of Gaza's 2.3 million people within the besieged territory, where U.N. agencies say there is no safe place to flee.

Egyptians began voting Sunday in a presidential election in which President Abdel Fattah al-Sisi faces no serious challenger and is certain to win another term, keeping him in power until 2030.

The election has been overshadowed by the Israel-Hamas war in Gaza. Almost all Egyptians' attention has been on the war on their country's eastern borders and the suffering of Palestinian civilians in the coastal enclave.

Iran warned Saturday of the threat of an "uncontrollable explosion" of the situation in the Middle East, after the United States vetoed a U.N. Security Council resolution calling for a ceasefire in the Gaza war.

Hossein Amir-Abdollahian, the top diplomat of the Islamic republic, also appealed for the immediate opening of the Rafah border crossing with Egypt to enable humanitarian aid to be sent into the Gaza Strip.

Israeli warplanes struck parts of the Gaza Strip overnight into Saturday in relentless bombardments, including some of the dwindling slivers of land Palestinians had been told to evacuate to in the territory's south.

The latest strikes came a day after the United States vetoed a United Nations resolution demanding an immediate humanitarian cease-fire in Gaza, despite it being backed by the vast majority of Security Council members and many other nations. The vote in the 15-member council was 13-1, with the United Kingdom abstaining.

The United States has vetoed a United Nations resolution backed by almost all other Security Council members and dozens of other nations demanding an immediate humanitarian cease-fire in Gaza. Supporters called it a terrible day and warned of more civilian deaths and destruction as the war goes into its third month.

The vote in the 15-member council was 13-1, with the United Kingdom abstaining. The United States' isolated stand reflected a growing fracture between Washington and some of its closest allies over Israel's monthslong bombardment of Gaza. France and Japan were among those supporting the call for a cease-fire.

Four pro-Hezbollah fighters were killed on Friday in an Israeli drone strike on their car in the south of Syria, a war monitor said.

The four fighters "working on behalf of Hezbollah" were killed in Madinat al-Baath town in the province of Quneitra, close to the Israeli-annexed Golan Heights, the Syrian Observatory for Human Rights head Rami Abdel Rahman told AFP.