Eritrea has detained local staff members working for a UN mission to monitor a peace accord between Ethiopia and Eritrea, thus violating the accord, the UN said on Thursday.
Eritrea has also restricted the movement of vehicles of the UN Mission to Ethiopia and Eritrea (UNMEE), the body said, in another sign of tension between it and Eritrean authorities.
UN peacekeepers patrol a 15-mile (25-km) buffer zone along the unmarked, 620-mile (1,000-km) border between the two Horn of Africa countries whose war in 1998 to 2000 was triggered by a dispute over the small Ethiopian border town of Badme.
The UN has previously criticised the March 5 closure to UN troops of a main highway linking the Eritrean capital Asmara to Barentu, a town south-west of it.
"An UNMEE vehicle was stopped on Friday inside Asmara town and local staff working for the UN were removed and arrested," UNMEE spokesman George Somerwill said in a video conference with reporters in Addis Ababa and Asmara.
"Some of those arrested were released but two are still in detention," Somerwill said those detained were local staff.
He said Eritrea had said that it was looking for draft dodgers when asked about the arrests.
"The Eritrean action is in violation of the UN convention and the Status of Force Agreement (SOFA)," Somerwill said, adding that the arrests had disrupted the peacekeepers' work.
"Following the incident, up to 20 percent of UNMEE local staff did not report to work," he said.
The UN has said the closure of a main highway hampered its work because it is a main supply route for Sector West (the western region) and this restriction on UNMEE's freedom of movement is in contravention of the Algiers Agreement.
The Algiers agreement, signed in 2000, ended the two-year border war between the two countries that killed more than 70,000 people.
Demarcation of their disputed border has been indefinitely postponed since Ethiopia rejected a ruling by an independent boundary commission that said Badme was part of Eritrea.
Abrahaley Kifle, the Eritrean commissioner responsible for co-ordinating with the peacekeepers, has said the road had been closed because the peacekeepers had overstepped their mandate.