Sinwar, who last month replaced assasinated Hamas leader Ismail Haniyeh, said in a letter to the group's Yemeni allies that "we have prepared ourselves to fight a long battle of attrition".

Deadly fighting meanwhile raged on in the Gaza Strip, where medics and rescuers said Israeli strikes on Monday -- which the military has not commented on -- killed at least two dozen people.

The latest strikes came as Israeli Defence Minister Yoav Gallant warned that prospects for a halt in fighting with Hezbollah militants in Lebanon were dimming, yet again raising fears of a wider regional conflagration.

Senior Hamas official Osama Hamdan told AFP at the weekend the group "has a high ability to continue" fighting despite losses, noting "the recruitment of new generations" to replace killed militants.

Sinwar, in his letter to Yemen's Houthis, threatened that Iran-aligned groups in Gaza but also elsewhere in the region including Lebanon and Iraq would "break the will of Israel" after more than 11 months of war.

Independent UN rights experts warned that Israel risked becoming an international "pariah" over its actions in Gaza and called on Western countries to ensure accountability.

Israel's barbaric war on Gaza has killed at least 41,226 people in Gaza, mostly women and children.

Deadly strikes
 

In central Gaza, survivors scoured debris Monday after a strike on the Nuseirat refugee camp.

Ten people were killed and 15 others were wounded when an air strike hit the Al-Qassas family home in Nuseirat in the morning, said a medic at Al-Awda Hospital, where the bodies were taken.

"My house was hit while we were sleeping without any prior warning," said survivor Rashed al-Qassas.

Gaza's civil defence said six Palestinians were killed in a similar strike at night on a house belonging to the Bassal family in Gaza City's Zeitun neighbourhood.

Emergency services later reported six more deaths, with Al-Awda Hospital saying it received the bodies of three people killed in Israeli strikes on Nuseirat.

The Gaza war has drawn in regional allies across the Middle East, including Hezbollah in Lebanon and Yemen's Houthis, who on Sunday claimed a rare missile attack on central Israel which caused no casualties.

Netanyahu in response said: "They should have known by now that we charge a heavy price for any attempt to harm us."

In July, a Houthi drone strike killed a civilian in Tel Aviv, at least 1,800 kilometres from Yemen, prompting retaliatory strikes that caused significant damage and deaths at Yemen's rebel-controlled Hodeida port.

Since November the Houthis have targeted Israel and its perceived interests in stated solidarity with Palestinians in Gaza, launching strikes that have disrupted global shipping through vital waterways off Yemen.

In a televised speech, the Houthis' leader said the rebels and their regional allies were "preparing to do even more".

"Our operations will continue as long as the aggression and siege on Gaza continue," Abdul Malik al-Huthi said.