The barrier, whose legality is being debated by the world court in The Hague next week, is expected to eventually stretch more than 700 km by the time it is completed at the end of next year.

The 180-km segment completed so far -- a montage of razor wire, electronic fencing, concrete and ditches -- has cut off villages from markets, medical services and schools in the northern West Bank.

It has resulted in the confiscation of 11,4000 dunums (2,850 acres - 1,140 hectares) of privately-owned Palestinian land and in the destruction of 102,320 trees, a report by the UN Office for the Coordination of Humanitarian Affairs (OCHA) found.

This land, which employs one quarter of the population there, is some of the West Bank's most fertile, and yields around 900,000 dollars per square kilometer, more than double the amount from other areas of the West Bank and Gaza Strip.

The barrier has also limited access to water in an area whose wells are some of the best of the western aquifer.

OCHA estimates that some 40,000 acres (16,200 hectares) of "high-income Palestinian land" will be affected by the wall in the northern West Bank alone.

The UN organization's field workers documented cases around the town of Qalqilya, where villages are severed from the main social, education, economic and health service center as a result of the eight-meter (25-foot) high wall which completely encircles the town.

"Whereas residents of these villages were once within three-five kilometers (two-three miles) of the hospitals, schools and markets of Qalqilya, they now face a journey or more than 20 kilometers and the need to pass through an IDF (Israeli Defence Forces) checkpoint into Qalqilya," said OCHA.

OCHA drew similar conclusions about the barrier's impact around annexed east Jerusalem.