Ethiopian Prime Minister Meles Zenawi expressed serious concern on Wednesday over restrictions imposed by Eritrea on United Nations peacekeepers patrolling the two countries' disputed border.
Speaking to journalists in the Ethiopian capital, Addis Ababa, Meles said the restrictions were a violation of a peace agreement signed by the two countries, adding that the UN "should take necessary measures to restore the status quo".
His comments came days after UN peacekeepers said the restrictions imposed on 5 October had prevented them from ensuring that there was no renewed military build-up along the border separating the Ethiopian and Eritrean armies.
Eritrea banned helicopter flights by peacekeepers in its airspace in the buffer zone and also restricted some UN night patrols on its side of the 1,000-km long Temporary Security Zone (TSZ).
The restrictions have prompted the UN to scale back its outposts in the border region from 40 to 18, effectively reducing its ability to monitor the border.
UN Secretary-General Kofi Annan warned on Monday that if Eritrea continued to impede peacekeeping operations, the UN could pull its troops out of the TSZ.
The TSZ was established after a peace agreement signed in 2000 in Algiers that ended the 1998-2000 war between the Horn of Africa neighbours, in which some 70,000 people lost their lives.
Meles also said there had been a slight increase in the number of Eritrean militia in the TSZ and had raised the matter with the UN.
"The scale has increased in recent days and this is a matter of concern to us," the prime minister said. "We have reason to believe these so called militia are members of the Eritrean Defence Force in a different uniform and a different guise."
Under the terms of the peace deal, no Eritrean troops are allowed in the 25 km-wide TSZ - a buffer zone in Eritrean territory separating the two countries and patrolled by 2,800 UN peacekeepers.
"We are aware of this development and it is our contention this is not a new phenomenon," he added. "We have raised this issue with the UN mission from the very time they arrived. It is not new despite the slight increase in numbers and scale."
The region is extremely tense because the two nations have been unable to agree on a final border despite a legal ruling by an independent boundary commission; the main sticking point being the fact that the ruling awarded one border town, Badme, to Eritrea in April 2002.
In September, the head of the UN Mission in Ethiopia and Eritrea, Legwaila Joseph Legwaila, said the unresolved border dispute could once again lead to war if the UN Security Council and the African Union did not do more to find a solution to the stalemate.