Official estimates put the death toll from the Armenian earthquake at up to 60,000 Monday, and hopes waned that any more survivors would be found. A second relief plane crashed near the Armenian capital, killing seven people.

Renewed political trouble also broke out, with Armenian activists reporting clashes with troops over the arrest of several nationalist leaders.Before dawn Monday, a Yugoslav military plane crashed while trying to land at Yerevan airport with medical supplies - the second crash of a relief plane in as many days. On Sunday, a Soviet military transport plane crashed as it approached the airport at Leninakan, a city hard hit by Wednesday's quake. Seventy-eight people died.

All seven crew members aboard the AN-12 cargo plane died in Monday's crash, First Deputy Aviation Minister Boris Banyukov said. Local reporters said the plane crashed at 4 a.m. because the pilot mistook a well-lit highway for a runway.

Both plane crashes followed a warning in the military newspaper, Red Star, that the airspace in the quake zone south of the Caucasus Mountains was overcrowded, with more than 300 flights a day, far more than air traffic controllers are used to.

"Several planes are circling at any one time, waiting for the signal to land. In these conditions, we need precision and rigid coordination," the newspaper said.

Tass said nine crew members and 69 soldiers were killed in the Sunday crash. It did not say what caused the crash, how many people were aboard or if there were any casualties on the ground.

The Yugoslav plane was part of an international relief effort. Council of Ministers spokesman Lev Voznesensky told a news conference in Moscow that 38 relief planes have arrived from abroad, with the most - six - from France. He and other officials said 923 specialists from abroad with 216 search dogs were working in the disaster area.

Meanwhile, a spokesman for the Geneva-based League of Red Cross and Red Crescent Societies said in Yerevan there was little hope more survivors would be found in the rubble piled high in several Armenian cities, including Leninakan, near the quake's epicenter, and Spitak, which was virtually wiped out.

The spokesman, George Reid, said only trapped people who managed to find water and had an air supply would survive.

An Associated Press reporter visiting Spitak, where 25,000 people lived, found a nearly deserted wasteland. She said only a few hundred residents remained.

Bitter cold weather was forecast for Armenia overnight, worsening conditions for the 500,000 people left homeless by the quake. The Soviet Meteorological Center said the temperature in Yerevan would drop to 14 to 23 degrees Fahrenheit.

Hundreds of bonfires provided the only heat for some people who have lived on the streets since the quake.

The rescue effort, drawing workers and supplies from about 40 nations, has been hampered by shortages of equipment and haphazard organization, some officials said. Some aid proved useless. A crane sat idle beside the ruins in Leninakan. Workers said it was too small.

Without electricity or water, Red Cross rescuers worked around the clock by the eerie light of campfires. On Sunday, with the aid of search dogs, they pulled out of the rubble a man in his 30s who had broken bones in his legs.

Soviet President Mikhail S. Gorba-chev and international rescue workers warned of the danger of epidemics breaking out. But one relief official from the United Nations, Sverre Kilde, said the danger was substantially reduced by subfreez-ing temperatures in most of the region, which would inhibit the growth of disease-carrying organisms.

Gorbachev wound up a two-day visit to the disaster area Sunday and called the earthquake, which measured 6.9 on the Richter scale, "a grave disaster, simply a tragedy."

Doctors Without Borders, an international relief organization, said in Amsterdam that Health Minister Yevgeny I. Chazov told workers the quake had claimed 50,000 to 60,000 lives. The previous government estimate was 40,000 to 45,000.

The Soviet Embassy in Washington said about 500,000 were left homeless and 6,000 people were hospitalized. It said 1,500 people had been rescued.

Mayor Emil Kirokofyan of Lenin-akan told a group of foreign correspondents that recently constructed apartment buildings were not built to withstand such a severe temblor _ even though Leninakan is in an area of frequent earthquakes.

Gorbachev promised residents of the disaster zone that the government would begin an investigation of why new apartment buildings crumbled so easily while older buildings remained standing after the quake.

He also accused "provocateurs" of using the consequences of last week's quake to create instability in the region and insisted, "They must be stopped."

One Armenian activist who avoided arrest, Raphael Popoyan, said by telephone Monday that three demonstrations were staged Sunday in the Armenian capital of Yerevan.

He said all were protesting the arrest of leaders of a committee that has spearheaded a drive to annex Nagorno-Karabakh, a predominantly Armenian enclave in Azerbaijan. In one demonstration, troops and demonstrators began fighting, and several were wounded on both sides, Popoyan said.

A dozen tanks were parked in Yerevan's central square Sunday night.