Israeli forces carried out fresh airstrikes Wednesday in the Gaza Strip, a day after comments from Israeli officials about expanding ground fighting sparked concern from the United Nations about the safety of civilians.

Wednesday’s fighting included Israeli ground operations and airstrikes in Gaza City, in the northern part of the Gaza Strip where Israel initially focused its campaign to eliminate the Hamas militant group.

After moving south to the Khan Younis area, Israeli officials this week have signaled a push into parts of central Gaza, including areas home to multiple refugee camps.

Much of Gaza’s population has been forced from their homes by the fighting, with people crowding into overburdened shelters and scrambling to exit areas after Israel warns of impending military action. Humanitarian aid deliveries have also been limited by the violence, leaving shortages of food, water and fuel.

“There are no short cuts in dismantling a terrorist organization,” Israeli army chief Herzi Halevi said Tuesday, referring to Hamas.

The expansion of fighting in central Gaza prompted the United Nations Tuesday to voice alarm over Israeli attacks that killed more than 100 Palestinians in the span of two days this week.

“We are gravely concerned about the continued bombardment of Middle Gaza by Israeli forces, which has claimed more than 100 Palestinian lives since Christmas Eve,” U.N. Human Rights Office spokesperson Seif Magango said Tuesday.

“Israeli forces must take all measures available to protect civilians. Warnings and evacuation orders do not absolve them of the full range of their international humanitarian law obligations,” Magango said.

Residents reported airstrikes and shelling in the areas of the Nuseirat, Maghazi and Bureij refugee camps in central Gaza.

Radwan Abu Sheitta, who lives in Bureij, told The Associated Press by phone, “The bombing was very intense.”

Israeli army chief Halevi told reporters in a televised statement Tuesday from the Gaza border that the war would go on “for many months.”

“There are no magic solutions, there are no shortcuts in dismantling a terrorist organization, only determined and persistent fighting,” Halevi said. “We will reach Hamas’ leadership too, whether it takes a week or if it takes months.”

The White House said U.S. President Joe Biden and Qatari Emir Sheik Tamim bin Hamad Al Thani discussed increasing access to humanitarian aid in Gaza in a phone call Tuesday.

“The two leaders discussed the urgent effort to secure the release of all remaining hostages held by Hamas, including American citizens,” a White House statement said.

Qatar and Egypt mediated the brief cease-fire and hostage exchange between Israel and Hamas in late November. However, current diplomatic efforts have fallen short.

The White House said Israeli Minister for Strategic Affairs Ron Dermer met Tuesday with Secretary of State Antony Blinken and national security adviser Jake Sullivan for talks on several matters related to the conflict in Gaza.

A White House official said Sullivan and Dermer discussed transitioning to a different phase of the war to focus on high-value Hamas targets, and planning for the day after fighting ends, including governance and security in Gaza.

On Oct. 7, Hamas militants poured over the border with Israel and attacked southern Israeli communities, killing about 1,200 people, according to Israel. Hamas, designated a terrorist group by the U.S. and others, also seized around 240 hostages, of whom 129 remain in Gaza.

In response, Israel vowed to crush Hamas and launched an air, land and sea attack on Gaza. The Israeli offensive has left vast parts of Gaza in ruins and killed nearly 21,000 Palestinians, according to the Gaza Health Ministry.

The fighting has also displaced most of Gaza’s 2.3 million people, with many trying to find safety in overcrowded, U.N.-run shelters in southern Gaza.

The Israeli army said Tuesday that 158 Israeli soldiers have been killed inside Gaza since fighting began in October.

VOA’s Mykhailo Komadovsky contributed to this report. Some material for this report came from The Associated Press, Agence France-Presse and Reuters.