The United Nations Security Council has rejected an Ethiopian request for a new body to decide on its contested border with Eritrea.
Ethiopia is unhappy about losing Badme
The UN "regretted" Ethiopia's position and urged it to implement last year's border ruling.
Following a two-year border war which left 70,000 people dead, a commission ruled that the town of Badme where the war began, belonged to Eritrea.
Ethiopia has refused to accept the ruling and last week, Ethiopian Prime Minister Meles Zenawi asked the UN to set up a new border commission.
He warned that the commission's "unacceptable" decision could lead to "another round of war" and therefore the UN had an obligation to get involved.
He however told the BBC that he was committed to resolving peacefully the worsening border dispute with Eritrea.
On Thursday Eritrean Foreign Minister Ali Said Abdella told the UN General Assembly in New York that "Ethiopia has wilfully crossed the red line and set in motion an irreversible process to scuttle the peace agreement altogether."
In a one-page response to the Ethiopian request the Security Council reminded Ethiopia that it had committed itself under the 2000 Algiers Agreements "to accept the boundary decision as final and binding".
The UN also urged both sides to resume talks over their dispute.
The border is manned by more than 4,000 UN peacekeepers.
After chairing recent military talks between the two sides, UN force commander General Robert Gordon warned that the peacekeeping operation risked ending in failure unless speedy steps were taken to mark the border.