INTERACTIVE Eritrea: A close look Ethiopia: A close look

ADDIS ABABA, Ethiopia (CNN) -- Ethiopia claimed new battlefield success in its border war with Horn of Africa neighbor Eritrea on Friday, answering calls for a cease-fire with the sound of artillery.

Ethiopia's government said it was gaining ground on Friday and would not stop fighting until it regained contested territory along its northern frontier, where Eritrea occupied disputed territory last year.

"The sovereignty and territorial integrity of Ethiopia is being restored," government spokeswoman Selome Taddesse said Friday. "Ethiopia does not want anything more beyond reclaiming its invaded land and it will not accept anything less."

Both countries rejected requests from the U.N. and European Union on Thursday to stop the fighting. The U.N. Security Council also urged all countries to halt the sale of arms and munitions to Ethiopia and Eritrea.

Eritrea says it has simply defended its positions from Ethiopian offensives and claims to have inflicted heavy casualties in beating back the attacks.

"Eritrea did not start the war and consequently cannot be held responsible for it," the Eritrean Foreign Ministry announced Thursday, adding that the country "has and shall exercise the legitimate right of self-defense."

The long-simmering dispute erupted into renewed combat last Saturday after an eight-month lull. The fighting has been fierce as ground troops, backed by air power and heavy artillery, clashed along the rocky and mountainous border between the two countries.

Each country blames the other for the renewed fighting, which is scattered along several fronts along the 1,000-kilometer (600-mile) frontier.

Eritrea gained independence from Ethiopia after a 1993 referendum. The two countries were allies until last May. Despite their struggling economies, both sides have large, well-equipped armies.

Diplomats see prolonged war

Military analysts say the war is likely to get worse and could prove disastrous if both sides deploy their full military might.

U.N. envoy Mohamed Sahnoun warned Thursday that the heavily armed countries might ignite "the first high-tech war in Africa." Sahnoun said he was optimistic when he arrived in Ethiopia and Eritrea last week to seek a diplomatic solution, but now says the pessimists were right.

Sahnoun -- an Algerian diplomat who is friends with both Ethiopian Prime Minister Meles Zenawi and Eritrean President Isias Afwerki -- called the war "nonsensical."

"I believed that given the kind of leadership they had, they would be able to resolve these problems," he said.

Diplomats say a settlement is almost impossible while the warrior nations' pride is inflamed.

"There are highly principled, exceedingly stubborn and almost irrecoverably committed people on both sides," said a senior Western diplomat. "That's not a good recipe for reaching a compromise."

The United States urged its citizens to leave both countries on Thursday, fearing that the antagonists might strike each other's capitals. William Clarke, the U.S. ambassador to Eritrea, said there was "a real prospect for continued fighting."

Reuters contributed to this report.

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