U.N. Secretary-General Kofi Annan is urging Eritrea to immediately reverse a decision to ban helicopter flights by United Nation's peacekeepers.

Mr. Annan said Wednesday the move would seriously limit the U.N.'s ability to carry out its work in the region.  He stressed that freedom of movement is a fundamental principle for all peacekeeping missions.

Eritrea gave no reason for the decision, which went into effect Wednesday.

Thousands of U.N. peacekeepers monitor a cease-fire between the two nations, who fought a two-year-long war over their shared border. 
In 2002, an independent boundary commission ruled on a new border.  Demarcation has stalled after Ethiopia objected to the decision to grant Eritrea sovereignty over the town of Badme.

Last month, a senior Eritrean official, Finance Minister Berhane Abrehe, warned the United Nations of renewed fighting with Ethiopia if the world body fails to resolve the dispute. 

Some information for this report provided by AFP.