A top UN official has warned that war between Ethiopia and Eritrea remains a possibility - five years after a deal ended their last conflict.
Ethiopia recently increased troop numbers along the border
UN peacekeeping head Jean-Marie Guehenno was speaking after meeting Ethiopian Prime Minister Meles Zenawi in the capital, Addis Ababa.
Mr Guehenno, however, welcomed Ethiopia's offer to withdraw troops from its disputed border with Eritrea.
Eritrea has condemned the UN's "meddling" in the tense Horn of Africa.
It said Ethiopia's recent offer to pull back its troops from near the border was irrelevant.
Mr Guehenno and his top military advisor Randhir Kumar Mehta are expected to travel to Eritrea on Tuesday.
"Nobody should be complacent in the present situation," he said.
"There is always a risk of war by miscalculation."
Dec 2000: Peace agreement
Apr 2002: Border ruling
Mar 2003: Ethiopian complaint over Badme rejected
Sep 2003: Ethiopia asks for new ruling
Feb 2005: UN concern at military build-up
Oct 2005: Eritrea restricts peacekeepers' activities
Nov 2005: UN sanctions threat if no compliance with 2000 deal
"We appreciate the decision of Ethiopia to pull back its troops from the frontline," he added.
Tensions along the disputed border have risen in recent weeks.
'Off the hook'
Eritrea is unhappy at reports that UN secretary general Kofi Annan has held several phone conversation with Mr Meles in recent days.
"This unwarranted political meddling is principally aimed at letting the Ethiopian regime off the hook," said a statement from the Eritrea foreign ministry.
Eritrea feels that the international community should put more pressure on Ethiopia to respect the decision of an independent commission that demarcated the border.
Eritrea and Ethiopia have recently been massing troops along the UN-policed border they fought over five years ago.
Last week Eritrea called for peacekeepers from European and North American countries to leave the country.
The Horn of Africa neighbours battled over their border in a 1998-2000 conflict that led to some 80,000 deaths.
Under a peace accord, the UN deployed a peacekeeping force in a 25km buffer zone on the Eritrean side of the border and the two states agreed to accept the findings of the border commission. But Ethiopia has not withdrawn its troops from the town of Badme, which the commission awarded to Eritrea.