With the key western town of Barentu already under the control of Ethiopian troops, Eritrea also faced a humiliating military reversal in its two-year war with its larger neighbor.

Ethiopian forces were pursuing the Eritrean army toward the provincial capital of Akordat, 40 miles northeast of Barentu, Ethiopian state radio and TV said Thursday evening.

Authorities urged residents of Akordat to evacuate. Mendefera, 37 miles south of Asmara, also was emptying in fear of advancing Ethiopian forces, said Worku Tesfamichael, director of the state-run Eritrean Relief and Refugee Commission.

Ethiopia's military campaign already has driven 550,000 Eritreans from their homes or the makeshift camps where they were sheltered, Tesfamichael said. With the addition of another 300,000 people already affected by a regional drought, Eritrea's needs were staggering, a U.N. official said.

"I don't think it would be less than a humanitarian crisis,'' said Simon Nhongo, the U.N. resident coordinator for Eritrea. Authorities have asked U.N. agencies here for help in obtaining relief supplies of food, water and tents.

In Nairobi, Kenya, the regional operations center for the U.N. World Food Program, spokeswoman Brenda Barton said getting the necessary relief food to Eritrea was "looking extremely problematic.''

The WFP relies on donor funds to pay for food as well as the means of transport to get it to those in need.

"We're not ruling out flying food in, but it's quite far to airlift from Nairobi,'' she said.

Sending food by ship would take longer. And Ethiopian media reported Thursday that the Ethiopian Air Force had bombed "selected military installations'' at Eritrea's Red Sea port of Massawa, 50 miles east of Asmara. Assab, the other Red Sea port 315 miles south of Massawa, is far from Eritrea's centers of population.

The latest round of fighting, which began May 12, has evolved from an initial Ethiopian occupation of Eritrean positions on the western front along the disputed 620-mile frontier to a full-scale invasion of uncontested Eritrean territory.

Nhongo acknowledged that Thursday, saying "the invasion has gone much beyond what was perceived as the original intention of Ethiopia.''

Ethiopia says its offensive is aimed at "dismantling'' the Eritrean army, securing territory around their disputed border and withdrawing.

But most Eritreans view the war as a David-versus-Goliath contest, with Ethiopia and its estimated 61.7 million people determined to subjugate upstart Eritrea.

Eritrea, with a population of 4 million people, gained independence from Ethiopia in 1993 after a 30-year guerrilla war. Self-reliance became the watchword of Africa's youngest state.

Meanwhile, thousands of demonstrators chanting "U.N. stop the war'' thronged the streets of Asmara, the capital, to protest a U.N. Security Council vote Wednesday imposing an arms embargo on both countries.

"The United Nations has passed a resolution that treats both the aggressor and victim equally. This is tantamount to supporting the aggressor,'' said a letter delivered to the U.S. Embassy by about 4,000 marching students and staff from Asmara University.

In Addis Ababa, the Ethiopian government condemned the embargo as favoring Eritrea, whom it called the original aggressor for its seizure of a border post in Badme in May 1998, setting off the conflict.

Many Eritrean protesters called on council members to send military help to fight Ethiopia for violating the U.N. Charter. Some were skeptical, saying racism and geography would deter tougher action.

The United Nations "should destroy the force that invaded us, as it did with Iraq when it invaded Kuwait,'' said Reka Daniel, a nursing student. "But they won't, and the reason is that this is Africa.''