Aid agencies are having trouble getting assistance to tens of thousands of Palestinians in desperate need of help following the Israeli incursions, U.N. officials said Tuesday.

Rene Aquarone, spokesman for the U.N. Relief and Works Agency that looks after Palestinian refugee camps, blamed Israeli security measures such as road blocks that restrict access to and limit movement within Palestinian areas.

"This is a crisis on top of an emergency," Aquarone said.

Aquarone said the agency was having to rely on its international staff to drive aid convoys because its Palestinian staff was barred from entering Israel.

"We are using everybody, from accounting staff to assistant secretaries-general, to make the convoys go," he said.

There are severe shortages of food, cement and animal feed, he said. The agency has donated 275 tons of flour to the Palestinian authorities because they are unable to obtain it themselves.

The lack of cement has forced the agency to stop 54 of 67 projects to generate jobs for Palestinians, he added.

The World Bank estimates $300 million of damage was done to the Palestinian territories during the incursion, Aquarone said. That includes $42 million in the Jenin refugee camp and $111 million in the town of Nablus.

Ross Mountain, the top U.N. relief coordinator in Geneva, said the biggest problems were unexploded ordnance — especially in Jenin and Nablus — and lack of shelter for those who have lost their homes.

The Palestinian deputy health minister, Munzer Sharif, has expressed particular concern about the lack of access for health workers, a spokeswoman for the World Health Organization said.

The collapse of immunization programs could lead to an outbreak of measles, while the lack of safe drinking water puts people at risk of getting cholera and other waterborne diseases, said the spokeswoman, Fadela Chaib.

Chaib a plane carrying emergency health kits that had been blocked in Amsterdam for nearly a week because Israel refused to let it land had now been diverted to Amman, Jordan.

"We are trying to get the kits to the West Bank by road," she said.

The World Food Program said it was trying to buy 2,800 tons of flour for an emergency distribution to 265,000 particularly vulnerable Palestinians.

Spokeswoman Christiane Berthiaume said WFP had not been able to make its normal deliveries of food for the past month.

"We have reached about 100,000 people, but the big majority of them — 94,000 — are in Gaza. In the West Bank we have only been able to reach people in institutions like hospitals," she said.

In Nablus, WFP estimates that 40,000 people — more than a third of population — are in urgent need of food aid, Berthiaume said. In Qalqilyah, 70 percent of the population is estimated to be living below the poverty line.