Israel has dramatically increased the flow of humanitarian supplies into Gaza, allowing on average 200 aid trucks a day, with some days as many as 400 trucks getting through, according to a top U.S. official.

Now, the focus needs to move beyond "counting trucks" and instead look to ensure the right supplies are being distributed throughout Gaza, according to David Satterfield, the State Department’s special envoy for Middle East humanitarian issues.

"Our first priority was -- because it had to be -- averting famine," Satterfield told reporters on Tuesday. "But we now need to move on beyond that goal to addressing the true needs: sanitation, availability of medicines, availability of potable water, the specialized care required for these vulnerable populations."

The United Nations this week is conducting a more detailed assessment on the needs for the civilian population, Satterfield said.

He said the U.N. needs more trucks that are cleared by the Israeli military to operate inside Gaza. He also said the Erez crossing between Gaza and Israel and an additional northern crossing must become accessible.

"Our work is focused every day, every hour, on seeing continuous progress made," he said.

-ABC News’ Anne Flaherty

The Israel Defense Forces has denied accusations from the Hamas-run Gaza Health Ministry that they buried at least 283 bodies in a mass grave near Nasser Hospital in Gaza.

"The claim that the IDF buried Palestinian bodies is baseless and unfounded," the IDF said in a statement. "During the IDF’s operation in the area of Nasser Hospital, in accordance to the effort to locate hostages and missing persons, corpses buried by Palestinians in the area of Nasser Hospital were examined."

"The examination was conducted in a careful manner and exclusively in places where intelligence indicated the possible presence of hostages," the IDF said. "Bodies examined, which did not belong to Israeli hostages, were returned to their place."

White House national security communications adviser John Kirby said Tuesday that the reports of mass graves are "deeply concerning," but the White House is not in a place to validate the reports.

"I wouldn't expect a U.S. investigation," Kirby said, adding, "We'll certainly talk to our Israeli counterparts."

Israel's Ambassador to the United Nations, Gilad Erdan, is claiming that more than 2,135 workers at UNRWA, the U.N. agency for Palestinian refugees, are members of Hamas or the Palestinian Islamic Jihad.

"Hamas has infiltrated UNRWA so deeply that it is no longer possible to determine where UNRWA ends and where Hamas begins," Erdan said. "Israel calls on the donor countries to refrain from transferring their taxpayers' money to UNRWA-Gaza, as these funds will go to the Hamas terrorist organization, and that violates legislation in the donor countries themselves."

This comes after an independent review of UNRWA released on Monday found the agency had policies in place to back up its principle of neutrality, but also found UNRWA had "serious gaps in implementation," The Associated Press reported. The report made recommendations to improve the agency’s neutrality.

The report also found that Israel hadn’t provided evidence to back up its claim that a significant number of UNRWA employees were members of Hamas or PIJ, the AP said.

Iranian Foreign Ministry spokesman Nasser Kanaani called Israel’s retaliatory strike against Iran last week "harassment" that has "caused no damage whatsoever."

"In our opinion, this issue is not worthy of addressing," Kanaani said Monday.

Hanna Siegel, niece of American hostage Keith Siegel, appeared on CBS' "Face the Nation" on Sunday morning and talked about the "surreal" feeling of seeing a recently released video purporting to show her uncle and talked about the possibility of a deal that would free him and other people thought to still be held by Hamas in Gaza.

"We've always believed that he was alive. We have to believe he's alive -- and his wife, my aunt, who was held for 52 days, [was] released in the deal that took place in November, she was with him," Siegel said. "When she came out, she told us he was alive, but this is the first time that we're seeing him, hearing him. It's surreal."

When asked about a potential hostage deal and temporary cease-fire between Israel and Hamas, Siegel said that she does think an agreement "can be reached" and pointed to an earlier deal that secured the release of her aunt and others during a brief pause in the war late last year.

Siegel also said that she believes the new release of purported hostage videos shows that Hamas is signaling they are ready to make a deal.

But she said that she is concerned that it might not be in Israeli Prime Minister Benjamin Netanyahu's "political interest to close a deal," though Netanyahu has said his goal is freeing the captives in Gaza as well as dismantling Hamas.

Siegel said that the Biden administration should "think about what they can do directly to bring our American citizens home."

She also said she has felt the "commitment from the Biden administration to get him back," referring to her uncle.

She became emotional talking about how her family missed her uncle during their Passover celebration and had a picture of him to pay tribute.

"I think there's so much swirling in the political realm that it's easy to forget that these are human beings. Keith is a grandfather, he's a husband, he's a brother, he's an uncle," she said.

She was asked whether her family is worried if a potential Israeli invasion of the Gaza city of Rafah, to further target Hamas fighters, could threaten her uncle's safety. She responded that she and her family are "very concerned."

-ABC News' Michelle Stoddart