An Israeli strike on Wednesday killed three of Hamas leader Ismail Haniyeh's sons in Gaza, as conflict rages in the Palestinian territory despite ongoing truce negotiations.

Hamas said in a statement that three of Haniyeh's sons and four of his grandchildren were killed in the air strike. Israel confirmed the killings, saying the sons were "Hamas operatives" who were "on their way to carry out terrorist activities."

The strike came as talks in Cairo dragged on, with Hamas still considering the latest proposal. A framework being circulated would halt fighting for six weeks and see the exchange of about 40 hostages for hundreds of Palestinian prisoners.

U.S. President Joe Biden, speaking at a news conference on Wednesday, said, "It's now up to Hamas. They need to move on the proposal that's been made."

Reacting to the strike that killed his sons and grandchildren, Haniyeh told Al Jazeera, "If they (Israel) think that targeting my children at the peak of these talks and before the movement's response, if they think that this will force Hamas to change its positions, they are delusional."

"Our demands are clear and specific, and we will not make concessions on them," Haniyeh said.

Israel's offensive in the past months has killed at least 33,482 people in Gaza, mostly women and children, according to the Hamas-run health ministry.

Israeli troops would nevertheless enter Rafah and return to Khan Yunis, from which they withdrew several days ago, said Israeli war cabinet member Benny Gantz.

The army would have to fight for years to come "in the Gaza Strip and in the West Bank, and on the Lebanon front," Gantz added.

As the conflict rages, there has been a growing chorus of international criticism aimed at the lack of aid entering the territory.

Humanitarian groups have accused Israel of using starvation as a weapon in the conflict, where UN experts say half the population is facing "catastrophic" food insecurity.

Israel denies the charges, and has repeatedly blamed the UN and aid organizations for distribution problems.

On Wednesday, Israel's Defense Minister Yoav Gallant said they are planning on distributing aid to Gaza through a new crossing and a port just north of the besieged territory.

"We plan to flood Gaza with aid and we are expecting to reach 500 trucks per day," Gallant said.

He also vowed to "streamline security checks" that aid organizations had blamed for choking the flow of aid through six months of the conflict.

Israel promised last week it would open the Erez crossing in the north after a tense telephone call between Biden and Israeli Prime Minister Benjamin Netanyahu in which the U.S. president demanded "immediate action" on aid.

But it is understood Israel's trucks will not use the crossing, with the country's media reporting that the government feared protests from far-right groups who are against any aid reaching Gaza.

(With input from agencies)