"The humanitarian fallout from the escalation of violence in the Middle East is increasingly daunting," said Tom Fletcher, UN under-secretary-general for humanitarian affairs and emergency relief coordinator.

UNITED NATIONS, March 3 (Xinhua) -- Falling missile and drone debris, restricted airspace and hostilities are driving up civilian casualties, damaging infrastructure and disrupting essential services in the Middle East, UN humanitarians said on Tuesday.

"Humanitarian operations across the region are being severely affected by insecurity, supply chain interruption and airspace closures," the UN Office for the Coordination of Humanitarian Affairs (OCHA) said. "The movement of humanitarian personnel remains restricted."

The office said that in Iran, local authorities and the Iranian Red Crescent Society reported that strikes since Saturday affected more than 1,000 locations, resulting in about 790 deaths and nearly 750 injuries. Some strikes reportedly hit dense residential areas, indicating damage to civilian infrastructure.

Stephane Dujarric, chief spokesman for UN Secretary-General Antonio Guterres, told reporters at a regular briefing on Monday that Guterres is following the situation with great concern.

"He is particularly worried about the multiplication of new fronts," said Dujarric. "We are also witnessing an increasing number of civilian casualties and a severe humanitarian impact on the well-being of people throughout the region."

The spokesman said the continued attacks on energy infrastructure in the Gulf can have a dramatic impact on the global economy, which remains highly dependent on fossil fuels.

He said the secretary-general finds activities along the Israel-Lebanon Blue Line, patrolled by members of the UN peacekeeping force in the region, UNIFIL, particularly worrisome.

"Over the past two days, our peacekeepers from UNIFIL have recorded dozens of rockets and missiles fired into Israel claimed by Hezbollah and several airstrikes and incidents of firing from south of the Blue Line from Israel into Lebanon," Dujarric said.

Despite the escalating situation in the region, OCHA said Israeli authorities reopened Kerem Shalom/Karem Abu Salem crossing on Tuesday for the entry of 500,000 liters of fuel and humanitarian assistance arriving through Israel and Egypt.

The office said that approximately 300,000 liters of fuel per day are required to maintain critical humanitarian operations in Gaza, so it is essential that fuel continues to enter consistently until longer-lasting solutions to supply Gaza with power are secured. The Rafah and Zikim crossings remain closed, and international humanitarian staff rotations are still suspended.

In the West Bank, the office said that Israeli forces continued the closure of most checkpoints, severely curtailing the freedom of movement of Palestinians and their ability to access services and livelihoods. They also affect humanitarian partners' ability to deliver assistance and conduct their operations.

OCHA said that on Monday, Israeli settlers killed two and injured three Palestinians while raiding the village of Qaryut in Nablus.

"The humanitarian fallout from the escalation of violence in the Middle East is increasingly daunting," said Tom Fletcher, UN under-secretary-general for humanitarian affairs and emergency relief coordinator.

He said OCHA is scaling up operations where necessary and possible, activating contingency plans across Iran and the region, including Lebanon, the occupied Palestinian territory, Syria and Yemen.

"The limited presence of international NGOs and operational space in Iran makes the challenge there greater," said Fletcher in a statement issued in New York on Tuesday.

"Respect for international humanitarian law is being challenged and eroded again. Each time civilian infrastructure is struck, access is restricted and aid is politicized, the space for humanitarian action shrinks and it becomes harder to reach the communities we serve," he said.