July 30 (Bloomberg) -- The United Nations Security Council ended a peacekeeping mission monitoring the disputed border between Ethiopia and Eritrea, raising the threat of renewed war in the Horn of Africa.

The Security Council voted 15-0 to terminate effective tomorrow a mission begun in 2000 following fighting between the East African rivals that killed as many as 100,000 people. The UN, whose officials also blamed Eritrea for restricting peacekeepers inside the disputed territory's buffer zone, will remove 328 soldiers and military observers.

The decision could ``result in an escalation of tensions in the border area, with the risk of a resumption of open hostilities,'' Secretary-General Ban Ki-moon said in a report to the council.

Eritrea's restrictions on UN peacekeepers' freedom of movement, fuel supplies and supply routes made it impossible for them to implement their mandate, Ban's report said.

Eritrean and Ethiopian envoys to the UN didn't immediately return phone calls seeking a comment on the Security Council action.

``An end is being put to work of the UN, unfortunately, not because its mandate has been implemented but because it became impossible to implement it,'' Ambassador Jan Grauls of Belgium, who drafted the resolution, said to the Security Council. ``The UN was gradually restricted in its freedom of movement by Eritrea to the point of being forced to leave the buffer zone it was supposed to monitor.''

Former Allies

The standoff between the countries has worsened conflict in neighboring Somalia, where Ethiopia and Eritrea back rival factions. It has also led to internal instability in both countries as the two rivals support armed rebel groups in each other's territory.

The 2000 Algiers accord established an independent boundary commission to demarcate the border between the two countries and a UN peacekeeping force, known as UNMEE, to patrol a 25- kilometer (15.5-mile) buffer between the two armies.

The two sides fought as allies at the helm of different rebel groups that toppled Ethiopia's communist Derg regime in 1991. Eritrea won independence with Ethiopia's support in 1993, with economic disagreements and the border dispute leading to war five years later.

Eritrea, with a population of 4 million compared with Ethiopia's 78 million, has used the continuing crisis to conscript 35 percent of its productive adult population, according to a June report by the Brussels-based International Crisis Group.

To contact the reporter on this story: Bill Varner at the United Nations at wvarner@bloomberg.net

Last Updated: July 30, 2008 12:50 EDT