Doubts surround a proposed US mission to Eritrea, to discuss the border dispute which it is feared could start a new conflict with Ethiopia.
Isaias Afewerki insists Ethiopia comply with a border ruling
President Isaias Afewerki has refused to allow the team of diplomats and army officials to visit the border area.
But Eritrean officials have not ruled out the possibility of the US delegation coming to the country.
Eritrea has said the first step to peace must be Ethiopian compliance with an international border ruling in 2002.
Last month, Eritrea ordered United Nations peacekeepers from Western states to leave the buffer zone.
On Wednesday, Eritrean Information Minister Ali Abdu said a "high-level" Eritrean delegation had met US officials, including Assistant Secretary of State for African affairs Jendayi Frazer, in Washington on Monday and discussed "substantive issues".
Ms Frazer was expected to lead the proposed US mission to the Horn of Africa.
On Tuesday, a senior US State Department official told Reuters news agency: "The schedule is in flux. She is working out the details."
If Ms Frazer does not go to Eritrea, she is expected to begin her mission in Ethiopia, including a visit to the Ethiopian side of the border.
Some observers saw the US mission as the last opportunity to resolve the dispute, which led to a costly war between 1997 and 2000.
A senior Eritrean diplomat told the BBC that allowing the US to engage in shuttle diplomacy could be seen to undermine the 2002 ruling, which was final and binding.
The UN Security Council is considering scaling down the peacekeeping force which currently separates thousands of troops from the two countries who are deployed close to the border, raising fears of renewed conflict.
Earlier, UN peacekeeping head Jean-Marie Guehenno, who recently travelled to both countries, said the US had "the clout, the credibility to move the process forward".
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
UN Secretary General Kofi Annan reported back this month to the Security Council on resolution 1640, which carries the threat of sanctions against both countries if they do not withdraw troops they had sent to the border.
He presented them with six options, from leaving things as they are to pulling out.
The 1997-2000 war which ended with a peace agreement committing both sides to abide by the ruling of an independent commission which demarcated the boundary.
However, Ethiopia has not withdrawn its troops from the disputed border town of Badme, which the commission awarded to Eritrea.
Eritrea wants the international community to put more pressure on Ethiopia to comply with the ruling.