A chartered DC9 carrying Yugoslav tourists on a one-day excursion got caught in stiff winds and dense fog as it approached the Ajaccio airport and smashed into a mountainside yesterday. Police said all 168 passengers, many of them travel agents on a promotional trip, and six crew members were killed.

Ajaccio police said there were no survivors and that the victims included three children.

However, the Yugoslav company which owned the plane, Inex-Adria Airways, was unable to say exactly how many people were aboard. It said the craft was equipped to carry 175 passengers.

The company also said several ticket-holders canceled at the last minute when it left Yugoslavia and that several of the passengers known to be on board were infants who could have been seated on their parents' laps.

Although police said the plane carried 168 passengers, organizers of the trip said as many as 172 people held tickets for the flight.

Officials said the plane crashed into the west side of the fog-shrouded 4,543-foot-high Mt. San Pietro, about 30 miles from the airport and near the village of Casa Casalabriva.

The tour agency that organized the trip said it was meant as a promotional excursion to introduce Corsica to Yugoslavs. About 40 of those aboard the plane were travel agency employes, it said.