Eritrea has angrily dismissed an accusation from its long-time foe Ethiopia that it is in material breach of the Algiers Agreement.
Ethiopia has threatened to terminate the peace accord
The treaty ended their brutal two-year war in 2000 and set up a commission that redrew the disputed border.
Eritrea's information minister told the BBC that the warning was "irrelevant".
If Ethiopia did pull out of the treaty, it might imply that it would no longer comply with the commission's ruling that Badme be awarded to Eritrea.
Ethiopia has failed to hand over the town of Badme which sparked the 1998 war, which killed some 80,000 people.
"Eritrea has nothing to do on this issue and as far as Eritrea is concerned, everything that has been said is irrelevant," Eritrean Information Minister Ali Abdu told the BBC.
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
"The Eritrea Ethiopia Boundary Commission is entitled and mandated to demarcate the border, but the Ethiopian regime is refusing to abide by the rule of law," he said.
The BBC's Peter Martell in the capital, Asmara, says Eritrea also denies backing terrorist groups targeting Ethiopia, claiming such accusations are a smokescreen for Ethiopia to divert attention from its failure to accept the border ruling.
Earlier this month, Eritrea said that it would pull back thousands of troops from the officially demilitarised border buffer zone; lift restrictions on United Nations peacekeepers and a ban on helicopter flights if Ethiopia agreed to enforce its end of the border ruling.
But Ethiopia says occupying the demilitarised zone and restricting the movement of the UN amounts to a material breach of the treaty.
Ethiopian foreign ministry sources stress that the letter, copied to the UN Security Council, is merely a formal notification, and the desired outcome would be for Eritrea to return to compliance so that no further action would follow.
Our correspondent says with the boundary commission due to close in November tensions are rising, adding to fears of a return to war.
Eritrea, which won its independence after a 30 year liberation struggle from Ethiopia, knows how bad war can be, and has said it will do everything in its power to avoid it, our reporter says.
But it has also stressed that it will not tolerate any infringement on its sovereignty or territorial integrity.