PARIS, Nov. 5— On the morning of Sept. 14, 1954, in the Ural Mountains about 600 miles southeast of Moscow, the Soviet military exploded an atomic bomb in the air near 45,000 Red Army troops and thousands of civilians as part of a military exercise.

How many people were killed or maimed or became ill as a result of the exercise may never be known. But a film of the test recently obtained from secret Soviet military archives sheds new light on the often reckless nuclear testing during the cold war and the use of people as guinea pigs, nuclear specialists say.

Among the disclosures of the film, parts of which were shown in Paris last month, are that the Soviets in a single test exposed their troops to radiation levels 10 times as high as the maximum then permitted for a whole year for American troops. It also discloses that the troops were exposed to high radioactivity for an extended time, at least the whole day. 'Imitation' Atomic Blast?

The purpose of the exercise, as explained by the film's official narrator, was to test whether troops could fight a battle in an area immediately after it was hit by an atomic bomb.

A committee of Soviet veterans is seeking Government compensation and special medical treatment for what the veterans say are years of radiation-induced illnesses, and the film provides the first public documentary proof that the test took place. Veterans were recently told by Russian generals that the explosion was an "imitation" atomic blast.

The Soviet newspaper Pravda first reported the secret test in October 1991 and since then veterans have discussed it openly.

The explosion took place near the village of Totskoye. The military's cameras recorded the explosion as it happened, 1,150 feet in the air, with the mushroom cloud forming almost directly above troops in makeshift shelters less than two miles from the blast's center.

The film documents both the cataclysm in the air and, up close, the aftermath on the ground, with images of flaming houses, scorched animals and mangled military equipment. Soon after the shock waves subsided, troops with little or no protective gear were filmed storming through an inferno of dust, heat and radiation.

During the cold war, all the nuclear powers deliberately exposed some troops to radiation in atmospheric tests to see how soldiers would function, even though many of the effects of radioactivity were already known. Records show that the United States carried out such experiments in Nevada and the South Pacific, France did so in the Algerian desert and the Soviet Union in the Arctic and Kazakhstan. And on all sides, it is now known, tests also sent radioactive fallout into inhabited areas.

The Soviet Union is believed to have made 137 atmospheric tests. American and European nuclear experts say no other nuclear test anywhere has come to light that matches the scale of the 1954 Totskoye exercise.

According to the United States Defense Nuclear Agency, the United States conducted 235 atmospheric tests of nuclear weapons from 1944 to 1962, exposing some 200,000 military and civilian personnel of the Department of Defense to some degree of radiation. Degrees of Exposure

United States officials say that the amount of exposure varied because the 200,000 included support staff and other workers and that the Americans' exposure to radiation was far shorter and lower in intensity than what people were exposed to at Totskoye.

The officials add that the Defense Department has been trying to identify and contact the Americans who were exposed for a medical study under the auspices of the National Academy of Sciences.

A Finnish film company, Lindoc, said it had bought the film from Russians who obtained it from military archives that have not been opened. It was shown at an environmental film festival in Paris last month as part of a documentary called "Human Nuclear Guinea Pigs."

According to a report by Inter Press Service in Moscow, the United States Central Intelligence Agency knew about the test by 1977 and "gained access" to the film years ago. The United States Air Force Magazine published a brief account of the test early this year.

The bomb, which had the power of 20,000 tons of TNT and was comparable to the bomb the United States dropped on Hiroshima, was set off at 9:33 A.M. on Sept. 14, 1954, between the cities of Kuibyshev (today called Samara) and Orenburg in eastern Russia, the film said. A Million People Nearby

"All the guests from the Socialist countries, all the defense ministers were there," said Ivan Skvortskov, a former military officer who appears in the film. He said they watched from a mountain command post 10 to 12 miles from the explosion site.

At the time, about a million people lived within 100 miles of the test site. Nuclear specialists said the extent of the radioactive fallout would have depended on weather conditions. Kuibyshev, about 80 miles to the west of the site, had about 800,000 inhabitants in the 1950's and Orenburg, about 100 miles to the east, had about 265,000. Three miles from the explosion site was the village of Totskoye, and less than 20 miles away the small town of Sorochinsk, where villagers in the documentary said many people later developed cancer and other illnesses attributed to radiation.

Similar reports have also come from Americans who lived downwind from atmospheric tests, among them inhabitants of Utah and of the Marshall Islands in the South Pacific.