The Jenin refugee camp in the occupied West Bank is heading in a "catastrophic direction", the UN agency for Palestinian refugees said Tuesday, adding that residents had "endured the impossible".
The Israeli military launched a major offensive in the West Bank on January 21.
On Sunday, the army said that it had killed at least 50 since it launched the operation, while the Palestinian health ministry in Ramallah said Israeli forces have killed 70 people in the territory since the start of the year.
The operation has also seen troops levelling buildings in a refugee camp adjacent to Jenin.
"The camp is going into a catastrophic direction," UNRWA spokeswoman Juliette Touma told reporters in Geneva.
"Large parts of the camp were completely destroyed in a series of detonations by the Israeli forces. It is estimated that 100 houses were destroyed or heavily damaged," she said, speaking from Amman.
"The residents of this particular camp have endured the impossible."
She added: "This detonation that happened on Sunday was when children were supposed to go back to school.
"When it comes to UNRWA, 13 schools in the camp and the surrounding areas continue to be closed. That affected 5,000 kids in that area."
Touma said UNRWA's services inside Jenin camp have been interrupted for several months and stopped completely in early December.
UNRWA said it received no prior warning of the detonations, as contact between staff and Israeli authorities is no longer permitted.
After Israel accused UNRWA of providing cover for Hamas fighters, legislation severing ties with the agency came into force on Thursday -- a move likely to hamper the agency's vital services after 15 months of war in Gaza.
The agency is banned from operating on Israeli soil, and contact between it and Israeli officials is also forbidden.

Ambulances carrying the bodies of Palestinians killed during an Israeli raid, arrive for the funeral, in Jenin, in the Israeli-occupied West Bank, on Monday. REUTERS

Smoke rises during an Israeli army operation in the Jenin camp for Palestinian refugees in the north of the occupied West Bank on Monday. AFP

A Palestinian walks next to the rubble on a damaged road during an Israeli raid, in Jenin, in the Israeli-occupied West Bank, on Sunday. REUTERS

Israeli soldiers walk along a road during a military raid in the al-Fara camp for Palestinian refugees, south of Jenin in the occupied West Bank, on Sunday. REUTERS

Israeli army armoured vehicles move along a road during a military operation in the Jenin camp for Palestinian refugees in the north of the occupied West Bank on Monday. AFP