War Brings Ethiopia to Verge of Fall : Rebellion: In an impassioned speech, President Mengistu says the ‘motherland is on the verge of collapse.’

With rebel groups closing in, embattled Ethiopian President Mengistu Haile Mariam has admitted his country is on the verge of collapse.

Urging the people in an impassioned speech to Parliament on Thursday to rally and save the nation, Mengistu for the first time confirmed rebel reports of fierce fighting north of the capital, Addis Ababa, and the Red Sea province of Eritrea.

“Citizens must realize . . . that their motherland is on the verge of collapse in the face of various conspiracies,” Addis Ababa radio quoted him as saying.

Mengistu said the fighting would decide whether Ethiopia will survive as a united sovereign state.

Rebels linked to the Tigre People’s Liberation Front, or TPLF, say they have killed nearly 22,000 government troops in the past three weeks, while Eritrean independence guerrillas have virtually cut off Mengistu’s 2d Army of 120,000 men.

Military analysts in Addis Ababa say the army is isolated outside the Eritrean capital, Asmara, and constantly harassed by guerrillas. Its only link to Addis Ababa is by air, and they say it no longer receives sufficient supplies.

A senior Western diplomat told a news correspondent in Addis Ababa last week that the army was “encircled and must be thoroughly demoralized and dejected. Meanwhile, the rebels are gradually tightening the noose.”

The Eritrean rebels, who in February captured the Red Sea port of Massawa, are now reported closing in on Asmara airport.

“If that goes, then it is as good as over,” said the diplomat, adding that for the first time in 29 years of warfare the rebels would control the entire province.

In his speech, Mengistu said the government setbacks followed an agreement between the Eritrean People’s Liberation Front and the TPLF to launch a joint offensive “to divide and disintegrate the country.”

He declared: “The choice before citizens is obvious. It is either to struggle for the unity and territorial integrity of Ethiopia or to see its downfall and destruction.”

Diplomats in Addis Ababa, contacted by telephone from Nairobi, said Mengistu was trying to appeal to the strong sense of nationalism among most Ethiopians. But they doubted that he would succeed.

Political analysts say Mengistu lost more support last month when 12 highly respected top military officers were executed for involvement in an attempted coup in May, 1989.

They said the executions, carried out in the cellar of the presidential palace, sparked the first open expression of anti-government sentiment seen in the capital for years.

Meanwhile, concessions by the Ethiopian government to try to revive the stalled peace process have been met with skepticism by the rebels, who accuse Mengistu of playing for time.

Earlier this month, the government announced it would give in to a key demand of the Eritrean rebels and invite U.N. observers to attend peace talks.

So far, no date has been fixed for the talks, sponsored jointly by former President Jimmy Carter and former Tanzanian President Julius Nyerere, although neither of the two main rebel groups has ruled out attending.