Making the announcement, Ethiopian president Negasso Gidada vowed to press on with the fighting until the eviction of enemy forces from its territory.

He was speaking in a radio and television broadcast to usher in Friday's 8th anniversary of the defeat of Col. Mengistu Haile Mariam's Derg regime, which ruled Ethiopia for 17 years.

Negasso said Ethiopia will use force to fully regain its sovereignty ''if the dictatorial regime of (Eritrean president) Issaias Afeworki remains defiant to withdraw from our sovereign territories in accordance with the OAU peace plan.''

An official statement Thursday night also claimed that Ethiopian forces ''successfully repelled' successive attacks by five Eritrean brigades on Ethiopian positions on the western front near the Mereb River Tuesday and Wednesday, killing 865 enemy forces and wounding 1,600 others.

During the 22-24 May offensive in the same locality by four brigades, Ethiopia claimed to have killed more than 400 soldiers and wounding 1,500 others, bringing the toll during five days of fighting to over 1,265 dead and 1,600 wounded. There was no independent confirmation of the figures given by the Ethiopian authorities.

The statement, however, said during the fighting Tuesday and Wednesday, Ethiopian forces captured ''large amounts of light and heavy armaments and radio communication equipment.'' Negasso stated Ethiopia would continue to reinforce its defence forces ''to guarantee national sovereignty and territorial integrity.''

Eritrean guerrillas defeated Derg forces and entered Asmara 24 May, 1991 while their allies, under the leadership of the Tigray People's Liberation Front of Meles Zenawi, captured Addis Ababa 28 May.

The Eritreans under Issaias did not join the Ethiopians in a transitional government formed in July 1991. Instead, they formalised their separation from Ethiopia in a referendum on independence in April 1993.

The two governments closely cooperated for a time until differences surfaced over trade and the use of the common currency, the Ethiopian birr. The use of the latter was terminated when Eritrea issued its own currency, the nakfa, in Novermber 1997.

The border dispute came to light when Ethiopia announced on 12 May, 1998 of ''unprovoked aggression'' by Eritrean forces and occupation of parts of its territory on the Badme/Shiraro front in the north-west. Mediation attempts by numerous governments as well as the OAU and the UN have failed to reconcile the two neighbours so far.

The UN-supported OAU peace plan, which both Ethiopia and Eritrea have accepted, is said to be the best hope for ending the hostilities.

Ethiopia said it killed 865 enemy troops and wounded 1,600 more in a two-day battle which began on Tuesday near the Mereb river on the key Badme military front.

``The Eritrean forces once again initiated hostilities on May 25 and 26 in the hope of capturing a strategic post near the

Mereb river but Ethiopian forces repelled the Eritrean attack,'' government spokeswoman Selome Taddesse said late on Thursday.

But Eritrea blamed Ethiopia for starting the new battle and said its own forces had won the day.

It said 785 Ethiopian troops were killed in five days of heavy fighting stretching back to last week on the Badme front and that 1,800 were wounded.

``The fighting was quite heavy,'' said Eritrean presidential adviser Yermane Gebremeskel. ``The Ethiopians were trying to occupy some areas which are no-man's-land,'' he said. ``Maybe they wanted to control some strategic areas or hills which would be useful later.''

Eritrea said its forces killed 405 Ethiopians, wounded 825, and captured four in fighting on Tuesday and Wednesday alone.

There was no independent confirmation of either side's claim, but diplomats said it was clear heavy clashes had taken place in the border region after a two-month lull.

The United Nations Security Council says it is alarmed by reports that foreign countries are sending weapons to Somalia, and has urged the country's rival factions to allow humanitarian aid to reach those in need.

The council did not name the countries it alleged were violating the 1992 arms embargo on Somalia, but correspondents say that Ethiopia and Eritrea back opposing Somali clans and are reported to be supplying them with arms.

The council said it was alarmed at the serious deterioration in the political, military and humanitarian situation in Somalia.

It urged the opposing factions there to stop fighting and co-operate with regional efforts to achieve a lasting settlement.