The Western Somalia Liberation Front announced today that Dire Dawa, a strategically located railroad town in the disputed Ogaden region of Ethiopia, is surrounded by its forces and called its fall "imminent."

The announcement, broadcast over Radio Mogadishu, said that an Ethiopian relief column of 500 soldiers sent to bolster the besieged town had been wiped out before reaching its destination.

Meanwhile, the Ethiopian government, in what appeared to be an admission of impending defeat, appealed to member states of the Organization of African Unity and the United Nations today to intervene to halt the alleged Somali invasion of southeastern Tthiopia.

Ethiopia maintains that regular Somali army forces are fighting in the disputed border Ogaden region. Somalia has denied this, saying that only insurgents of the Western Somalia Liberation Front are involved.

The fall of the Dawa, a town of about 50,000 and the main transit point on the Addis Ababa-Djibouti railroad, would be a major blow to Ethiopia - in effect costing it all control over the railroad, which has already been cut in several places by the Somali insurgents.

A Western Somalia Liberation Front spokesman said yesterday that the other two main centers in the disputed territory - Harrar and Jigjiga are also surrounded and predicted their fall by the end of this month.

Today, the front also announced that two smaller towns, aware and Degahabur, had been captured, effectively completing the Somali insurgent's takeover of the Ogaden region proper, which Somali claims as part of a "greater Somalia nation" incorporating all Somali-speaking peoples.

Altogether, Somalia's historical claims cover all or large parts of four southeastern Ethiopian provinces, almost one third of the land mass of that country.

All indications are that the Ethiopian regular army and units of Ethiopia's newly established 100,000-man "peasant army" have been driven from almost all of the territory Somalia seeks to control. Ethiopian efforts to organize a counteroffensive seem to have stalled, and fears here that the Ethiopian army might invade Somalia have subsided.

Ethiopia is reported here have only about one army brigade and an undetermined number of peasant militiamen defending Dire Dawa. If reinforcements are now being cut off and the town is isolated, as the front claims, it is doubtful that Dire Dawa can hold out long.

One Arab source said he thought the city would fall "within the next week."

News services reported these other developments:

Ethiopia complained to the United States and Britain about their decision to sell arms to Somalia. The charges d'affaires of both countries in Addis Ababa reportedly told Ethiopian Foreign Minister Feleke Gadle Giorgis that their governments had agreed to the sales only "in principle" and that the weapons would be defensive.

A delegation of Western Somalia Liberation Front leaders left Baghdad after five days of talks with leaders of Iraq's ruling Baath Party. Abdallah Hassan Mahmoud, secretary general of the front, said there was "an identity of views" on topics discussed, including Iraqi support of the secessionist movement.

A spokesman for the Eritrean Popular Liberation Front said in Rome that Eritrean secessionists had captured Soviet-made arms in fighting against Ethiopian government forces in Eritrea Province. The spokesman said a few tanks, many rifles and enough hand grenades to arm 5,000 soldiers were seized when rebels captured Keren last month.

Residents of the town of Jigjiga in Harrar Province staged a rally to demand arms to fight the Somali backed forces, the Ethiopian News Agency reported.