The American Ballet Theatre and its dancers are perilously close to another labor dispute, one which may disrupt the company's upcoming season. The labor contract reached after a bitter three-month lockout in 1979 expires in two and one-half weeks and some dancers say they expect ABT to lock them out again.

The dancers and management are far apart: ABT's latest offer is a three-year contract with wage increases of 2 1/2 percent the first year and 5 percent in each of the subsequent years.

During the 1979 dispute, ABT's four-week December season at the Kennedy Center had to be canceled. On Monday, ABT and its dancers' negotiating committee will meet for only the fourth time this year to discuss wages and other issues. Several dancers fear this week that ABT may, at this meeting, hand their negotiators a lockout notice, effective Sept. 1.

ABT executive director Herman E. Krawitz yesterday declined to comment on a possible lockout.

"We expect some sort of a labor dispute," ABT soloist Frank Smith said this week. Smith, spokesman for the dancers and a leader of their negotiating team, would not rule out the possibility of a dancers' strike.

Earlier this week, 61 of ABT's 88 dancers met to discuss the negotiations and many of them came away from the meeting fearing a protracted dispute.

Some of the dancers are still outraged at the length of the 1979 dispute -- when the dancers, after charging ABT was trying to "starve" them into submission, finally won a wage increase of about 40 percent spread over three seasons. The dancers are also upset by events that occurred at the New York City Ballet in 1980.

At that time, one year after the ABT dispute, NYCB gave its dancers an approximate 43 percent wage increase over three seasons without any shutdown, protracted negotiations, harsh words or bitterness.

One ABT union leader said many dancers felt insulted by ABT's latest wage offer for this coming season and that based on this offer, the two sides seem hopelessly apart.

But yesterday, Krawitz made it clear that even he doesn't think too highly of the offer. "What the current offer is is of no consequence," he said. "What counts is what it takes to get an agreement and I know what it will take . . . "

Krawitz declined to elaborate but did say that since "there's a ritual and a reality" to ABT's negotiations, the reality may not yet be evident.

"I feel we will have an agreement," he said.

However, time is running short. The company will perform beginning next Tuesday for two weeks in Philadelphia -- its new summer home -- and the dancers will have to negotiate between performances and rehearsals. ABT is then scheduled to return to Manhattan to begin rehearsals for the upcoming season -- which is supposed to begin with a two-week engagement in Paris in October.

The dancers, however, say they have no intention of going to Paris -- even with satisfactory wage increases--because so far ABT has refused to promise them adequate food and expense allowances. This separate dispute is also pending.

Meanwhile, ABT, which has its own permanent orchestra in Manhattan for its lengthy seasons at the Metropolitan Opera House, has signed a new contract with its musicians. That contract grants the musicians a wage increase of about 10 percent per year, and, according to the dancers' leadership, the musicians will be earning -- including rehearsal pay, which the dancers don't now get -- an average of between $800 and $1,000 per week this season.

The minimum wage at ABT under the expiring contract is $405 per week for a corps dancer, $540 for a soloist and for principal dancers it is $650 per week for 40 weeks a year.

ABT is scheduled to appear twice this season in the Washington area, at the Kennedy Center for four weeks beginning the week of Dec. 5, and for one week at Wolf Trap beginning the week of Aug. 14, 1983.