Soviet and Afghan forces used information to round up rebel sympathizers in a tiny villlage 40 miles from Kabul and killed 12 by deliberately running them over with tanks, according to a reliable diplomatic report received here today.

After the men were killed, according to the report, their homes were stripped of all belongings, including furniture and food, and their families were left to fend for themselves.

The incident was given unusual credibility by analysts here. They cited the reliability of the sources who carried the report to the Afghan capital of Kabul.

"They are as close to eyewitness as you can get," said one diplomat who had studied the classified cables from Afghanistan that gave full descriptions of the sources.

With most Western journalists denied entry to Afghanistan, diplomatic reports have provided virtually the only information on developments in that country. Most of the reports, including the latest one, cannot be independently confirmed.

Diplomats said the incident in the village of Tangi Canyon in Wardak Province was part of a series of widespread search-and-destroy operations going on for the past two weeks under the guise of military maneuvers. The operations are believd to be an effort t root out rebel forces from the provinces around Kabul before the winter snows bog down Moscow's military machine.

Sources told diplomats in Kabul that the search parties in Tangi Canyon were directed by Afghans who, while remaining hidden in an armored personnel carrier, used a loudspeaker to send soldiers to specific houses in which rebels lived.

Villagers who reported the incident to friends in Kabul are convinced that the Afghans in the command personnel carrier were some of the four local activist members of the ruling Marxist People's Democratic Party, diplomats said.

According to the sources, the Soviet-Afghan military force entered the narrow canyon 11 days ago with tanks and armored personnel carriers, blocked escape routes and then began rounding up rebels whose names were on lists carried by the officers.

Twelve of the suspected rebels were singled out and crushed to death under the tank treads. The villagers then reportedly were threatened with harsh but unspecified punishments if they failed to send their young men to join the Army and if the older men did not join militia units.

Diplomatic reports reaching here from Kabul offered descriptions of other unconfirmed incidents in the search-and-destroy campaign. According to the reports, during the last two weeks the Soviets have substantially increased their military security within Kabul. The diplomats also repeated unconfirmed reports circulating in Kabul of seven assassinations of Afghan military officers, party workers and government sympathizers.

In the village of Hussain-Kot, about seven miles north of Kabul, diplomats said, Afghan soldiers on search-and-destroy missions are said to have cut a deal with villagers: the soldiers would give the village a clean bill of health in exchange for food.

The diplomats cited another major search-and-destroy operation by a large Soviet-Afghan force supported by many helicopters near the town of Sanglakh, about 30 miles west of Kabul. According to reports reaching Kabul, all the helicopters had Afghan Air Force markings but were piloted by Soviets in civilian dress, many of them wearing black leather jackets.

The houses in the area were reportedly thoroughly searched for weapons and rebels. The villagers also were warned against harboring or supporting insurgent bands that have been bedeviling Moscow's plans to pacify the country for the pro-Soviet government installed when 80,000 Soviet troops invaded the country last December.

The search-and-destroy operations were first signaled by an announcement Nov. 15 that military maneuvers would take place in Kabul Province and the nearby provinces of Parwan, Ghazni, Nangarhr.