"The world welcomed the New Year with celebrations and festivities, while we witnessed 2025 begin with the first Israeli massacre in the town of Jabalia just after midnight," agency spokesman Mahmud Bassal told AFP.

"Fifteen people were martyred and more than 20 were injured" in the strike on a house where displaced people were living, he said.

The Israeli military said it was looking into the reported strike.

Since October 6, the military has been conducting a major land and air offensive in northern Gaza, particularly targeting Jabalia and its adjacent refugee camp.

The military says it is an effort to prevent Hamas militants from regrouping there and it has killed hundreds of fighters, while rescuers in the area say thousands of civilians have died.

On Monday, UN human rights experts said the "siege" appears to be part of an effort "to permanently displace the local population as a precursor to Gaza's annexation".

Bassal said those living in the house were members of the Badra, Abu Warda and Taroush families who had sought refuge there.

Nearly all of Gaza's 2.4 million people have been displaced at least once since the war began on October 7 last year.

The dead and wounded from the strike in Jabalia were taken to Al-Mamadani Hospital, a rescuer said.

A relative said rescuers were still searching for any survivors.

"The house has turned into a pile of debris," said Jibri Abu Warda, adding that the strike hit at around 1:00 am (2300 GMT Tuesday).

He said the explosions shook the area, and rescuers reached the targeted house only in the morning.

"It was a massacre, with body parts of children and women scattered everywhere. They were sleeping when the house was bombed," Abu Warda said.

"No one knows why they targeted the house. They were all civilians."

- Fear of cold -

At Al-Mamadani Hospital, women wept over shrouded bodies in the morgue, some of them those of children.

"We don't want aid, we want the war to stop. Enough with the bloodshed! Enough!" said Khalil Abu Warda, a relative of the deceased.

The assault, which began on October 6 in Jabalia, has since expanded across the north of the territory.

On Friday, the military raided Kamal Adwan Hospital in Beit Lahia, emptying it of its last staff and patients.

The army said it had killed more than 20 suspected militants and detained more than 240 in "one of the largest" such operations it has conducted since the start of the war.

Those detained included the hospital's director, Hossam Abu Safiyeh, a 51-year-old paediatrician it described as a suspected Hamas militant.

The World Health Organization, Amnesty International and others have called for his immediate release.

"Around me there's nothing but rubble and destruction. People don't know what to do, don't know where to go. And they don't know how to survive," said Jonathan Whittall, a UN aid official in a video released after he visited the Indonesian Hospital in north Gaza.

The Israeli military has repeatedly accused Hamas of using hospitals as command centres, an allegation the militant group denies.

A report published Tuesday by the UN Human Rights Office said "insufficient information" has been made available to substantiate "vague" Israeli accusations of military use of hospitals.

Two further Israeli strikes in Gaza on Wednesday killed another 10 people, including children, the civil defence agency said.

Several displaced Gazans said they were facing not just Israeli bombardments but also falling temperatures and heavy rains, which have flooded thousands of tents across the territory.

"For three days, we haven't slept out of fear that our children would fall sick because of the winter, as well as fear of missiles falling on us," said Samah Darabieh, a displaced woman now living in Beit Lahia.

"Two days ago, they bombed Al-Wafaa hospital, which is behind us, and the shrapnel dropped here."

The Hamas-run territory's health ministry said seven children have died from the cold over the past week.

The war in Gaza began when Hamas attacked Israel on October 7 last year, resulting in the deaths of 1,208 people, mostly civilians, according to an AFP tally based on Israeli official figures.

Israel's retaliatory military campaign has killed at least 45,553 people in Gaza, most of them civilians, according to figures from the Gaza health ministry which the United Nations considers reliable.