Relief planes from around the world rushed emergency supplies into Armenia Friday to help victims of an earthquake that killed tens of thousands of people and left hundreds of thousands homeless.

A spokesman for Yerevan's Zvarnots airport said planes arrived Friday from France, Belgium and Bulgaria, and many more were expected. It was the first time disaster aid had reached the Soviet Union on such a scale.Soviet officials released no death toll two days after Wednesday's quake, but the Soviet ambassador in Britain, Leonid Zamyatin, said that about 80,000 people died in the southern republic of 3.3 million.

Speaking briefly in English to a delegation of Armenians at the Soviet Embassy in London, he said: "Our estimate is, but it's not an exact figure, that we have about 80,000 people who lost life in Armenia, and 2.5 million lost their homes." He added: "Many people are in hospitals, including children."

Official media gave less specific estimates.

Tass news agency said "the earthquake killed tens of thousands of people." Radio Moscow said: "It is believed that scores of thousands of people have died."

President Mikhail S. Gorbachev returned home to direct the growing relief efforts, which brought emergency food, medics, medical supplies and search equipment to the devastated region.

Gorbachev, who cut short a trip to the United States and canceled plans to visit Cuba and Britain, arrived in Moscow before dawn, Tass said. He was expected to travel to Armenia, but officials refused to specify when.

Tass reported a Swiss rescue team and 20 search dogs flew to Armenia with eight tons of rescue supplies. Swedish officials announced $1 million in rescue assistance, and Finland sent shipments of blood plasma.

President Reagan offered humanitarian aid, Cuban President Fidel Castro pledged to send construction workers, and Britain, France and Italy also dispatched rescue teams.

Leon Azruyan, an editor at the official Armenpress news agency in the Armenian capital, Yerevan, said he saw dozens of villages "totally destroyed." In Spitak, a city of 16,000 near Len inakan, "99 percent of the population is gone," he said.

"Helpless sobbing people are climbing on the wreckage of an apartment house, from which can be heard heart-rending cries for help," the Communist Party daily Pravda wrote from Leninakan, a heavily battered city near the quake's epicenter.

U.S. scientists said the quake measured 6.9 on the Richter scale, and a Soviet quake expert predicted more tremors would occur.

"We expect more tremors to take place soon," said Nikolai Shebalin, a spokesman for the Soviet Institute of Physics of the Earth. Tass quoted him as saying the tremors "should be less powerful" than the quake, which also rocked portions of the republics of Azerbaijan and Georgia.

Official Soviet media covered the disaster with unprecedented scope and speed.

In an interview Thursday on Soviet television, Premier Nikolai I. Ryzhkov appealed for aid to the area. He said rescue workers needed cranes and other heavy equipment to remove debris and look for survivors.

TV reports said two-thirds of Leninakan, a city of 290,000 on the Turkish border, were destroyed.

Spitak "was practically erased from the face of the Earth," said one television correspondent. Tass said half the buildings in Kirovakan, a city of 150,000, had crumbled.

It said the injured and those left homeless were being housed in tents, military barracks, officers' houses and clubs, garrisons and dining rooms.

Alexei Gartinsky, a senior official of the Soviet Red Cross, told ABC-TV's "Good Morning America" Friday that antibiotics, disposable syringes and blood supplies are needed. However, he said his organization has not issued an international appeal.

Friday and Saturday were declared days of mourning in Armenia. A special meeting of representatives of all 15 Soviet republics was called in Yerevan to discuss disaster relief.