Eritrea has written two letters to the United Nations this week, accusing it of failing in its duty to resolve the border dispute with Ethiopia.
More than 3,000 UN peacekeepers patrol the border
Ethiopia has not withdrawn its troops from land awarded to Eritrea by an international demarcation commission.
The demarcation followed a border war in which 70,000 people died.
President Isaias Afewerki accused the UN of exaggerating the humanitarian situation in Eritrea to disguise the unresolved border issue.
"We are watching with sadness the unacceptable and false campaign that you seem determined to set in motion to portray a humanitarian crisis in Eritrea," Mr Isaias wrote to UN Secretary General Kofi Annan.
"This campaign is apparently designed to cover up the failure of the United Nations to shoulder its legal responsibilities in the border conflict and to wrongly shift the blame to Eritrea," he said.
Referring to the continued presence of Ethiopian troops on territory awarded to Eritrea, Mr Isaias wrote: "The United Nations has, through its inaction, provided an umbrella for the forcible occupation of our sovereign territories."
Another letter to the Security Council describes how the UN has failed to maintain peace and security in the region and argues that the UN is complicit in tensions between Ethiopia and Eritrea, because they have failed to put any pressure on Ethiopia.
More than 3,000 UN peacekeeping troops patrol the border zone in accordance with the 2000 peace agreement, but Eritrea has recently imposed restrictions of the operations of the peacekeeping force.
Eritrea has rejected a plea from Mr Annan to lift a ban on peacekeeping flights along its tense border with Ethiopia.
Eritrea banned UN helicopter flights in its airspace on 5 October.
Eritrea is suffering from a prolonged humanitarian catastrophe, the UN says, with 2.3 million people facing a lack of food.
Mr Annan has warned that the UN may have to pull its troops out if the flight ban remains in place.
Eritrea became independent from Ethiopia in 1993, after Ethiopian and Eritrean rebel movements overthrew the Derg regime in Addis Ababa.