US President Donald Trump hailed a "tremendous day for the Middle East" as he and regional leaders signed a declaration meant to cement a ceasefire in Gaza, hours after Israel and Hamas exchanged hostages and prisoners.

Trump made a lightning visit to Israel, where he lauded Prime Minister Benjamin Netanyahu in an address to parliament, before flying to Egypt for a Gaza summit where he and the leaders of Egypt, Qatar and Turkey signed the declaration on Monday as guarantors to the ceasefire deal.

By Richard Cowan

WASHINGTON (Reuters) -U.S. President Donald Trump on Sunday questioned whether former UK Prime Minister Tony Blair would serve on a new "Board of Peace" that is intended to oversee the governance of Gaza, amid ongoing criticisms of Blair for his role in the Iraq War.

"I've always liked Tony, but I want to find out that he's an acceptable choice to everybody," Trump said, without naming specific leaders who could be weighing in on his choice of Blair.

A Gaza peace plan floated by the White House last month listed Blair as a member of the proposed board.

The world's tropical coral reefs have almost certainly crossed a point of no return as oceans warm beyond a level most can survive, a major scientific report announced on Monday.

It is the first time scientists have declared that Earth has likely reached a so-called "tipping point" -- a shift that could trigger massive and often permanent changes in the natural world.

By Alexander Cornwell and Nidal al-Mughrabi

JERUSALEM/CAIRO (Reuters) -U.S. President Donald Trump will receive a hero's welcome in Israel's parliament on Monday as a fragile Gaza ceasefire he helped to broker enters a fourth day, with the expected release of Israeli hostages and Palestinian prisoners marking tentative steps in a conflict long resistant to resolution.

WASHINGTON (Reuters) -U.S. President Donald Trump said on Sunday Israel's war in Gaza was over.

"The war is over, you understand that," Trump told reporters aboard Air Force One.

(Reporting by Kanishka Singh in Washington; editing by Diane Craft)

LONDON (Reuters) -Britain will provide a 20 million pound ($27 million) aid package to deliver water, sanitation and hygiene services in Gaza, Prime Minister Keir Starmer said on Sunday, as he arrived in Egypt for a world leaders' summit on ending the conflict.

Britain said the funding would be delivered through UNICEF, the World Food Programme and the Norwegian Refugee Council and was designed to reach those facing famine, malnutrition and disease.

US President Donald Trump declared Sunday that the "war is over in Gaza" as he headed on a high-stakes peace trip to Israel and Egypt.

Speaking to reporters on Air Force One at the start of the "very special" visit, Trump brushed off concerns about the ceasefire and hostage release deal between Israel and Hamas.

"The war is over. Okay? You understand that?" Trump, 79, said when asked if he was confident that the conflict between Israel and Palestinian militant group Hamas was finished.

RAMALLAH, West Bank (Reuters) -The Palestinian Authority is ready to work with U.S. President Donald Trump and former British Prime Minister Tony Blair on their effort to consolidate the Gaza ceasefire and start rebuilding, a senior Palestinian official told Blair on Sunday.

Trump's plan for ending the Gaza war holds out the prospect of the Palestinian Authority, based in the Israeli-occupied West Bank and led by President Mahmoud Abbas, eventually taking control of Gaza, but only after it completes reforms. Abbas lost control of Gaza to the Hamas militant group in 2007.

US President Donald Trump declared the Gaza war "over" on Sunday as he headed to the region to host a peace summit, while Hamas prepared to release surviving hostages after two years in captivity.

Under the US president's proposed roadmap, once the Palestinian militants have handed over the hostages, Israel will begin releasing around 2,000 detainees in exchange.

The United States, Egypt, Qatar and Turkey signed a declaration on Monday at a summit on Gaza as the guarantors of a ceasefire deal aimed at ending two years of war.

US President Donald Trump lauded the summit -- which he co-chaired with Egyptian President Abdel Fattah al-Sisi -- as a "tremendous day" for the Middle East, while Sisi said the Gaza deal opened a "new era of peace and stability" for the region.

Earlier on Monday, Trump gave a speech to Israel's parliament following the return of 20 surviving hostages held by militants in Gaza.