The United Nations human rights office has said the Israeli air attack on Gaza’s Jabalia refugee camp could amount to a war crime, amid growing horror at the rising number of civilians killed in the nearly month-long war.

The camp, in a densely-populated part of Gaza City, was hit by a missile on Tuesday, leaving a giant crater amid bombed-out buildings before it was then targeted in a second bombing on Wednesday.

The Gaza Government Media Office said at least 195 people had been confirmed dead with more than 100 thought to be missing beneath the rubble. Some 777 people were injured in the attacks, it added.

Israel said the attack targeted a Hamas commander.

“Given the high number of civilian casualties [and] the scale of destruction following Israeli air strikes on Jabalia refugee camp, we have serious concerns that these are disproportionate attacks that could amount to war crimes,” the Office of the United Nations High Commissioner for Human Rights wrote on X.

The comments follow a wave of condemnation from the United Nations, where officials expressed shock and horror at the attacks on Jabalia, Gaza’s largest refugee camp.

Secretary-General Antonio Guterres “is appalled over the escalating violence in Gaza”, his spokesman Stephane Dujarric said.

This includes “the killing of Palestinians, including women and children, in Israeli air strikes in residential areas of the densely populated Jabalia refugee camp”, Dujarric added.

The UN’s children’s agency, UNICEF described the attacks as “horrific and appalling”.

In said it was too early to know how many children were among the dead in Jabalia, but noted that more than 3,500 children had been killed since October 7 when Hamas attacked Israel, killing 1,400 people and taking 200 captive, and Israel began its bombardment of Gaza in response.

Gaza, controlled by Hamas since 2006, is home to about 2.3 million people who have lived under a blockade for 17 years.

“This is just the latest atrocity to befall the people of Gaza where the fighting has entered an even more terrifying phase, with increasingly dreadful humanitarian consequences,” Martin Griffiths, the UN humanitarian chief, said in a statement.

He said, “The world seems unable, or unwilling, to act,” adding that “this cannot go on. We need a step change”.

Israel said Jabalia was attacked because of a “vast” tunnel complex at the site, and that “many Hamas terrorists” had been killed, including local commander Ibrahim Biari, whom Israel accused of involvement in the October 7 attack.

Hamas claimed seven captives, including three foreigners, had been killed in the bombing.

Dujarric said that the secretary-general reiterated that all parties “must abide by international humanitarian law, including the principles of distinction, proportionality and precaution”.

He also called on them to “bring an end to this shocking violence, pain and suffering”.

The attacks on Jabalia came as the Rafah crossing on the southern border with Egypt was finally opened, albeit only for the most seriously injured and some foreign nationals.

The opening of the crossing also allowed Philippe Lazzarini, the head of the UN agency that works to help Palestinian refugees, to get into Gaza for the first time since the conflict began.

He met Palestinians taking shelter in a school.

Afterwards, he described the visit as “one of the saddest days” of his more than 30-year career as a humanitarian. He has worked previously in countries including Iraq, Somalia and Rwanda.

“The levels of distress and the unsanitary living conditions were beyond comprehension,” Lazzarini said in a statement. “Everyone was just asking for water and food.”

Lazzarini leads the United Nations Relief and Works Agency for Palestinian Refugees (UNRWA) and is the most senior UN official to be allowed into Gaza since October 7. More than 70 members of the agency’s staff have been killed since the bombardment began, and Lazzarini paid tribute to those still trying to meet the needs of Gaza’s people, describing them as a “ray of light”.

He reiterated his call for more international aid, and for a ceasefire.

“The current humanitarian response is by far not enough, nor does it match the huge needs of people in Gaza,” he said, noting the lack of fuel and its “devastating impact on hospitals, bakeries, water plants, and our operations. A humanitarian ceasefire is long overdue. Without it, more people will be killed, those who are alive will endure further losses, and the once vibrant society will be in grief, forever”.