World leaders have called for an immediate halt to violence in Gaza after a series of Israeli strikes on the Palestinian enclave on Tuesday.
The strikes killed more than 400 people, according to the Palestinian health authority.
The move has threatened to collapse a two-month ceasefire between Israel and Palestinian militant group Hamas.
The US has indicated it supports Israel's actions, with the acting US ambassador to the United Nations, Dorothy Shea saying Washington would back Israel in its next steps.
Both Israeli and American officials have blamed Hamas for renewed strikes and accused the Islamist group of refusing to release more of the 59 hostages it holds in Gaza.
But European and Middle Eastern governments have expressed concern the escalation could undermine efforts to end the conflict, which has been raging since Hamas' attack on Israel in October 2023.
The British government called on Israel and Hamas to implement their ceasefire agreement for Gaza "in full", urging all parties to "return urgently to dialogue" to end fighting.
"We want to see this ceasefire agreement re-established as soon as possible," said Prime Minister Keir Starmer's spokesman, adding that reported civilian casualties from Israeli strikes overnight were "appalling".
In a statement, the French Foreign Affairs department called for "an immediate end to hostilities".
"France condemns the Israeli strikes carried out since yesterday on the Gaza Strip, which have caused numerous civilian casualties," it said.
Italian Prime Minister Giorgia Meloni said the new strikes risked diplomatic efforts to return hostages to Israel.
"We are following with great concern the resumption of fighting in Gaza," she told the Italian senate.
She said the move "jeopardises the objectives we are all working towards: the release of all hostages and a permanent end to hostility, as well as the restoration of full humanitarian assistance in the (Gaza) Strip."
Qatari Prime Minister Sheikh Mohammed bin Abdulrahman Al Thani urged for countries to come together to compel Israel to implement an immediate ceasefire.
Qatar has been a key player in negotiating and mediating ceasefire negotiations between the two sides.
Egyptian President Abdel Fattah al-Sisi, whose country also helped mediate the truce in the Israel-Hamas war, condemned the strikes, branding them a "flagrant violation" of the agreement.
In a statement, his office said the strikes were part of "deliberate efforts to make the Gaza Strip uninhabitable and force the Palestinians into displacement".
In another statement, Egypt's foreign ministry called the strikes a "dangerous escalation which threatens to bring serious consequences for the stability of the region".
Concerns for humanitarian welfare of Palestinians
With the backing of the United States, Israel had been pressing for the return of the remaining hostages in exchange for a truce until after the Muslim fasting month of Ramadan and the Jewish Passover holiday in April.
United Nations Human Rights High Commissioner Volker Turk said the renewed bombardment would "add tragedy to tragedy".
"Israel's resort to yet more military force will only heap further misery upon a Palestinian population already suffering catastrophic conditions," he said.
[YOUTUBE: World reacts]Tahani Mustafa, a Senior Palestine Analyst with International Crisis Group said Israel's air strikes came as "no surprise", accusing Israel of conducting multiple violations of the ceasefire.
She told ABC's The World the hostages would have been safer if phase two had been enacted.
"It's really been these processes of humanitarian pauses and negotiations that has guaranteed their release," she said.
Reuters/AFP
