Talks between the trucking industry and striking Teamsters broke off late yesterday after two days of futile efforts to end a 6-day-old work stoppage that is crippling the nation's auto industry.

No date was scheduled for a resumption of bargaining, and chief federal mediator Wayne L. Horvitz said talks before next week are unlikely.

"At the moment we are . . . no closer than we were at the time the strike started," said Horvitz after the two sides mutually agreed to break off negotiations indefinitely, subject to recall by Horvitz.

Teamster President Frank Fitzsimmons, who said he refused to budge from the union's prestrike demands, claimed that further progress is unlikely until the industry's bargaining team is reorganized to include owners of major trucking firms.

Accusing chief industry negotiator J. Curtis Counts of incompetence and a lack of experience with trucking issues, Fitzsimmons said the two sides would be "spinning our wheels" until the industry team is reshaped.

In a statement later, he said he was not questioning the companies' right to choose their own bargaining agents but though owners should get involved. He also called on the companies to end their lockout of the union and return to negotiations when they want "progress."

Counts last night said he had no comment on Fitzimmons' statements.

The bargaining break-off came as the government issued a new report on the economic impact of the combined union strike and industry lockout, predicting that rapidly escalating parts shortages will force the auto industry to lay off more than 200,000 workers, at least one-quarter of its total work force, next week.

But the Labor Department analysis said there has been little if any, interruption in delivery of food and other crucial commodities, and officials said it would be about a week before disruptions become critical enough to warrant government intervention.

Intervention could come in the form of a governmental request to the courts for a back-to-work order and 80-day cooling-off period under the Taft-Hartley Act, which sanctions strike-stopping injunctions when the national health or safety is imperiled.

The Teamsters called selective strikes against 73 firms when agreement on a new three-year contract was not reached by last Saturday's deadline, and Trucking Management Inc. (TMI), the industry bargaining group, responded the next day with a lockout honored by nearly all its 500 member firms.

Industry sources claim that 235,000 of the 300,000 Teamsters covered by the master freight contract are locked out, but the union contends that the industry is exaggerating the success of the lockout.

Fitzsimmons said yesterday that nearly 1,000 firms, including one or two TMI members, have signed interim agreements based on the union's last prestrike demand-indicating that the union is making at least some headway in its divide-and-conquer strategy to force an industry capitulation.

There had been speculation by sources close to the talks that a settlement would not come until the two sides had gone through a "macho" test of strenght, probably lasting into next week.

The break-off not only threatens more economic disruption, probably extending beyond the hard-hit auto industry, but also bodes ill for the Carter administration's already enfeebled efforts to win union compliance with its voluntary wage restraint program.

Although Fitzsimmons said he thought the Teamsters' money demands would fit the guidelines, industry bargainer Counts said they exceeded guidelines and would be a "tremendously costly" impediment to the ability of TMI firms' ability to compete with nonunion operators.

Although the industry claims its final prestrike offer provided for wage and benefit increases in excess of 30 pecent over three years, the government calculates it at about 22.5 percent, or 7 percent annually, compounded over three years. This would be within the 7 percent-a-year wage standard, officials say.

The government calculates the union's last demand before the strike at 2 percentage points more than the industry's offer, hence 2 percentage points over the guidelines. Fitzsimmons said yesterday that the union had not deviated "one iota" from its earlier demand.

When the strike began, the two sides reportedly were separated by 25 cents an hour, a windfall the union would receive if it wins its demands for semi-annual rather than annual payments of cost-of-living increases. Horvitz said last night that the "total cost" of the package is at issue.

Teamsters covered by the master freight agreement currently get an average of nearly $10 an hour in wages, or $12.65 in average total compensation.

Trucking officials say they are reluctant to breach the guidelines for fear the Interstate Commerce Commission will deny rate increases to compensate for the added labor costs. They also fear loss of business-even bankruptcies if rates go too high, they say.