The Soviet government on Saturday called for a round-the-clock guard to protect key industrial plants in the troubled republics of Armenia and Azerbaijan against any further outbreaks of ethnic unrest.

A resolution passed by the Council of Ministers called on the authorities in the two republics to ensure that all enterprises were working normally and warned against attempts to disrupt key industrial plants and transport."A round-the-clock guard must be placed on major economic facilities, including power plants, oil and gas fields, pipelines, power lines, railways, civil aviation facilities, communications and water supply plants," Tass news agency quoted the resolution as saying.

It called on the governments of Armenia and Azerbaijan to organize "explanatory work" among the population and emphasised that anyone disrupting the economy of the republics could face criminal charges.

Soviet television reported a speech to the Communist Party Central Committee by Mikhail Gorbachev, who called for a change in atmosphere in the two republics as the only way to settle their differences.

Two weeks of upheaval have left 28 people dead and prompted thousands of Armenians and Azeris to flee their homes in each other's territories seek refuge in their own republics.

At least 63 people have died since the conflict first erupted over the disputed Azerbaijani territory of Nagorno-Karabakh, an area populated mainly by Armenians.

Gorbachev reiterated that Armenian demands for the transfer of the territory were unacceptable. "The problem must be worked out on the basis of existing borders," he said.

Gorbachev called on Armenians and Azerbaijanis to sit down together and discuss their differences. He also said the press in both republics should take a more responsible attitude and avoid whipping up tension.

Azerbaijani radio, monitored by the British Broadcasting Corp., quoted officials as saying that more than 78,000 refugees had flooded into the republican capital of Baku after fleeing from Armenia.

The report blamed rumors circulating in Baku about Armenian attacks on refugees for stirring up tension. On Friday, the radio said troops had broken up a crowd of some 1,500 Azeris trying to attack Armenians in the city.

Soviet television said on Saturday that the city was returning to normal, although groups of people were still gathering in the central Lenin square, where hundreds of thousands have joined in anti-Armenian protests over the past two weeks.

The capitals of both republics, as well as a number of other parts of Azerbaijan, including towns in Nagorno-Karabakh, have been under a state of emergency and curfew since the start of the latest clashes.

In the Armenian capital of Yerevan, an official told Reuters that some 40,000 refugees had arrived in the city. But he said the situation there was returning to normal.

Tass said Yerevan was calm, with enterprises working normally, although other parts of the republic were continuing to cause alarm.