Urgent actions are imperative to achieve an immediate, permanent cease-fire and to accelerate humanitarian aid delivery to Palestinians in the Gaza Strip, according to a leaders' statement on Tuesday, as the conflict is triggering wider spillover effects in the region.

The "Call for Action: Urgent Humanitarian Response for Gaza" conference in Sweimeh, Jordan, was co-organized by Jordan, Egypt and the United Nations on Tuesday to address the dire humanitarian situation in the Gaza Strip, where about 1 million civilians are in hunger and forcibly displaced.

The statement called for establishing an immediate, permanent cease-fire and the immediate and unconditional release of all hostages and civilians who are being illegally held captive, demanding their safety, well-being and humane treatment in compliance with international law.

"We cannot abandon Gaza," King Abdullah II of Jordan said at the conference.

The leaders expressed grave concerns at the enormous loss of life, the unprecedented civilian casualties and the unfolding man-made humanitarian catastrophe in Gaza, caused by the continuing lack of humanitarian access to civilians in need, according to the United Nations Office for the Coordination of Humanitarian Affairs.

"Humanitarian aid to the Palestinians in Gaza is imperative", said Haoliang Xu, under-secretary-general and UNDP associate administrator, on behalf of UNDP Administrator Achim Steiner, as stated on the United Nations Development Programme website.

In his remarks at the conference, Egyptian President Abdel Fattah El-Sisi welcomed the entry of sufficient and sustainable humanitarian aid into Gaza, as well as Resolution 2735 adopted on Monday by the UN Security Council.

On Wednesday, US Secretary of State Antony Blinken headed to Qatar for talks after Hamas submitted a response to a US-led proposal for a cease-fire.

Blinken, on a four-country tour around the Middle East to push Hamas to accept the truce proposal, will meet the top leadership of Qatar, which has been in communication with the Palestinian militant group.

Amendments proposed

Hamas, responding to the plan laid out late last month by the United States, proposed amendments late on Tuesday, including a ceasefire timeline and the complete withdrawal of Israeli troops from Gaza, according to a source close to the talks.

Egypt and Qatar said they had received Hamas' response, but did not disclose the content.

Hamas' response to a proposed Gaza cease-fire deal "opens up a wide pathway" to reach an agreement, Izzat al-Rishq, a member of Hamas' political bureau, said on Wednesday.

The movement's response is "responsible, serious and positive", al-Rishq added.

The US said Israel accepted its proposal, but Israel has not publicly stated this. As Israel continues its assaults in central and southern Gaza that are among the bloodiest in the conflict, Israeli Prime Minister Benjamin Netanyahu has repeatedly said Israel would not commit to an end of its assault in Gaza before Hamas is eliminated.

As the fate of a cease-fire hangs in the balance, Hezbollah fired a massive barrage of rockets into northern Israel on Wednesday to avenge the killing of a top commander, further escalating regional tensions.

Hezbollah said it fired missiles and rockets at two military bases in retaliation for the killing of Taleb Sami Abdullah, 55. Known within Hezbollah as Hajj Abu Taleb, he is the most senior commander killed since the fighting began eight months ago.

Hezbollah has traded fire with Israel nearly every day since the Israel-Hamas conflict began and says it will only stop if there is a truce in Gaza.

As air raid sirens sounded across northern Israel, the military said about 160 projectiles were fired from southern Lebanon, making it one of the largest attacks since the fighting began. There were no immediate reports of casualties.

Agencies and Xinhua contributed to this story.