Pan American World Airways announced yesterday that it has reached agreements in principle with three of its major unions on two-year contracts containing wage and productivity concessions.

Tentative agreements were reached yesterday with the Transport Workers Union, the International Brotherhood of Teamsters and the Independent Union of Flight Attendants, the airline said.

Agreements were announced earlier with the two other major unions representing Pan Am's pilots and flight engineers.

The new settlements were reached just hours after reports circulated that a Pan Am vice president had warned during negotiations that Pan Am Chairman C. Edward Acker would shut down the airline next month if agreements weren't reached. James A. Arey, Pan Am's system director of public relations, yesterday called the comment "labor rhetoric" that comes out during "the normal course of events" in negotiating a contract.

"It should have been restricted to the closed negotiating sessions," he said.

Shutting the airline down could have been "a possibility, a maybe, a what might happen" if the needed agreements weren't reached, Arey said. "It was not issued as an ultimatum or a last act."

Cost-saving agreements have been sought by the money-losing Pan Am as part of its overall financial recovery plan.

Although the terms of the new contracts weren't disclosed, they are likely to include provisions similar to those in the pilots' and engineers' agreements: significant work-rule changes and continuation of a pay freeze at levels set two years ago when employes accepted a 10 percent wage cut. The pilots also had accepted a provision tying the size of future pay increases to airline pilots.

Pan Am said yesterday that, because of the holidays, the ratification process will take place next month. The Transport Workers Union and the Teamsters Union have agreed to submit the new contracts to their members for ratification. The flight attendants will take their package to their executive board.

Paul Chorbajian, a Pan Am engineer and chairman of the Pan Am Joint Labor Council, a group comprised of all the unions, said yesterday that the actions of the five labor groups reaffirms their commitment to support the company.

"As Pan Am's largest shareholder, we are all dedicated to doing whatever is necessary to return Pan Am to profitability in l983. . . and we will succeed," he said.

In another industry development, New York Air announced that Texas Air Corp., its parent company, has agreed to make a substantial equity investment in the New York carrier, an action that sharply improves its working capital and equity positions and largely eliminates its short-term debt. When the financing is complete, Texas Air will own 80 percent of the stock of New York Air, up from 67 percent.