After nearly one year of study, the Men's International Professional Tennis Council has reached an agreement with the Association of Tennis Players that will make mandatory drug testing a part of the men's tour beginning in 1986.

The council and the players, meeting in London, announced yesterday that players will be tested at two of the five two-week tournaments on the tour. The two tournaments will be selected at random from among the Lipton Players International and the four Grand Slam events: the French Open, Wimbledon, the U.S. Open and the Australian Open.

All players entered in the two tournaments selected will be tested. If they refuse testing, they can be suspended by the pro council. If they test positive and refuse treatment, they also would be subject to suspension.

The implementation of the new drug policy was expected after council administrator Marshall Happer recommended that a policy be established during the council's last meeting in September.

Also expected was the council's decision to file a countersuit against ProServ Inc., International Management Group and Volvo. The three groups sued Happer and the council last summer. ProServ and IMG each manage both players and tournaments and are locked in a battle with the council over the running of the pro tour.

Happer says there is a conflict of interest when the people running a tournament also manage many of the players in the tournament. ProServ and IMG say Happer is trying to remove them from tournament management so the council can monopolize the Grand Prix tour.

While the lawsuit is another step in a developing fight, the agreement between the players and the council is a milestone. It marks the first time a players group in a major sport has agreed to regularly scheduled mandatory drug testing.

The new rule was recommended by the ATP and will be enforced by the council. It specifically covers cocaine, heroin and amphetamines.