A 1998-2000 conflict between the Horn of Africa neighbours killed some 70,000 people, after which the Permanent Court of Arbitration in The Hague was asked to determine the border.
The court's Eritrea-Ethiopia Boundary Commission will issue a statement later on Friday with its conclusion.
The commission's likely decision, to leave the two countries to sort out their differences alone, had raised fears of a repeat of the border conflict, but Ethiopia's Prime Minister Meles Zenawi dismissed such concerns.
"We will never, ever go to war with Eritrea , unless there is full scale invasion," Meles said on Thursday.
"I do not think that the Eritrean government would launch a full scale invasion, because it would be suicidal for them."
Tensions between the countries have ratcheted up in recent weeks with the approach of the deadline to physically mark their disputed frontier.
Asmara and Addis Ababa have disputed their shared frontier since a 2002 ruling by the court's boundary commission gave Eritrea the key town of Badme.
Meles dismissed the passing of the commission's deadline and said the so-called virtual demarcation "is a legal nonsense."
Last November, the commission said it was fed up by the lack of progress with the border and gave both nations one year to make moves to mark the frontier or it would fix it on international maps.
The United Nations says Eritrea and Ethiopia have moved thousands of troops and heavy weapons to the 1,000-km (620-mile) frontier since the border commission gave its deadline.
The United Nations and the United States have urged both nations to show restraint.
On Thursday, the U.S. State Department said that Secretary of State Condoleezza Rice will visit Ethiopia next week for meetings on the conflicts in the region.
Rice is scheduled to meet leaders from the African Great Lakes region -- Rwanda, Burundi, Democratic Republic of Congo and Uganda -- in Addis Ababa on Dec. 5.
(Reporting by Tsegaye Tadesse in Addis Ababa)
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