The French ambassador and more than 80 members of his mission have left Laos, reducing the size of the French Embassy in Vientiane to six on orders of the Laotian government.

The government in Vietiane had accused France of supporting anti-Communist resistance, and ordered the French Embassy reduced to the size of the Laotian Embassy in Paris.

Frenc sources said the Laotian government accused France last week of harboring anti-Communist conspirators among the thousands of Laotian refugees who have emigrated to France since a Communist government took power in Vientiane in 1975. Laos is a former French colony.

Other diplomatic sources here said resistance forces have been causing "serious trouble" for the Laoitan government. They cited reports of an attempt on the life of Premier Kaysone Phomvihane, a grenade attack on the Soviet ambassador's residence and frequent ambushes of Vietnamese troops in Laos last year.

Analysts here estimate that 30,000 to 40,000 Vietnamese troops are stationed in Laos.

Fifty-one of the French nationals who left Laos yesterday are young volunteers attached to the French cultural and educational services. The rest are diplomatics and their dependents.

A small U.S. Embassy continues to function in Vientiane.