Thousands of Palestinians in the occupied West Bank risk being displaced as the Israeli authorities threaten to tear down their homes and in some cases entire communities, a UN agency said on Wednesday.

"To date, more than 3,000 Palestinian-owned structures in the West Bank have pending demolition orders, which can be immediately executed without prior warning," the UN Office for Coordination of Humanitarian Affairs said in a report.

"At least 10 small communities throughout the West Bank are at risk of being almost entirely displaced due to the large number of pending demolitions orders," OCHA said.

Most of the orders were issued because there were no construction permits, which Israeli authorities only seldom grant to Palestinians.

The buildings are located in so-called Area C, which makes up more than 60 percent of the West Bank and which is under full Israeli control.

In the first quarter of 2008, Israeli authorities demolished 124 structures as compared with 107 for the whole of 2007, leading to the displacement of 435 Palestinians, 135 of them children, OCHA said.

"Children are frequently disproportionately affected by the demolition of their homes and the subsequent displacement of their families," the study said.

Over 94 percent of applications for building permits in Area C submitted by Palestinians between January 2000 and September 2007 were denied, according to official data.

During this period 5,000 demolition orders were issued, and over 1,600 Palestinian buildings were actually demolished.

"The denial of permits for Palestinians on such a large scale raises the fear that there is a specific policy by the authorities to encourage a 'silent transfer' of the Palestinian population from Area C," the Israeli settlement watchdog Peace Now said in a recent report.

In the 2000 to 2007 period, 2,900 demolition orders were issued against Israeli settlers in the West Bank, but just seven percent were implemented, according to Peace Now.

Some 283,000 settlers live in Area C, which is also home to 70,000 of the 2.3 million Palestinians who live in the Israeli-occupied West Bank.