GENEVA - The World Health Organization (WHO) said the Israeli military attacked its staff residence and main warehouse in Gaza on Monday, a move the agency said severely undermined its ability to operate in the region and accelerated the collapse of the local health system.

The WHO said in a statement that its staff residence in the city of Deir al-Balah in Gaza was attacked three times on Monday, and its main warehouse was destroyed. It condemned the attacks "in the strongest terms".

WHO Director-General Tedros Adhanom Ghebreyesus said on X that the Israeli military entered the agency's premises, forcing women and children to evacuate on foot, while male staff and family members were "handcuffed, stripped, interrogated on the spot and screened at gunpoint".

Two staff members and two of their family members were detained. Three were later released, while one remains in custody, said Tedros, who called for the immediate release of the detained staff member and urged full protection for all WHO personnel.

He also called on member states to help ensure a sustained and regular flow of medical supplies into Gaza.

"A ceasefire is not just necessary, it is overdue," he said.

On Monday, the Israeli military sent tanks into parts of Deir al-Balah following a warning issued the previous day ordering residents, including displaced people living in tents, to evacuate in anticipation of immediate action.

Tens of thousands of displaced Palestinians were in Deir al-Balah when the evacuation order was issued, according to initial estimates from the UN Office for the Coordination of Humanitarian Affairs.

Over 20 Western nations, as well as the EU, on Monday called for an immediate end to the war in Gaza, noting that the suffering of civilians in Gaza "has reached new depths."

"We condemn the drip-feeding of aid and the inhumane killing of civilians, including children, seeking to meet their most basic needs of water and food," read the statement.

The Palestinian death toll from Israeli attacks on the Gaza Strip has surpassed 59,000 since the outbreak of the conflict on Oct 7, 2023, WHO's Gaza-based authorities said on Monday.