The Reagan administration has caught a burst of flak from Sen. Sam Nunn (D-Ga.) and others for its moves to embrace labor unions with a history of corruption. The most recent instance was the president's July 18 address to a gathering of the International Longshoremen's Association (ILA), where he praised its president for "integrity and loyalty" to friends and country.

Days before, in a continuing Labor Department investigation into an embezzlement scheme in Cleveland, the uncle of Teamsters union President Jackie Presser was indicted. The uncle, Allen Friedman, later told NBC News that he is ready to testify against his nephew.

"Jackie Presser should have been in jail dozens of times, going back 30 years," Friedman said. Earlier, Friedman had refused to testify against Presser. Meanwhile, the administration has been courting Teamsters political support.

Nunn, ranking minority member of the Senate's Permanent Subcommittee on Investigations, issued a statement noting these developments and listing 10 ILA officials who hold union office despite criminal convictions. He is pushing for legislation that would require union officials to step down if they are convicted of a crime.

Labor Secretary Raymond J. Donovan said in an interview yesterday that the administration will continue to press union leaders to clean up corruption wherever it exists, but he defended the administration's relationships with the unions and said its "open-door policy" will continue.

In the case of the ILA, he said, "There's been a history they are not very proud of. But does that mean they should be alienated for the rest of their existence?"

In the case of the Teamsters, he noted that Presser has promised a "new day," with strong action to clean up corruption.

Commenting on the furor through a spokesman, Presser said, ". . . It's the political season again. Beyond that, I have nothing to discuss." OMB vs. LABOR . . . Department officials, in an unusual alliance with Rep. Barney Frank (D-Mass.), chairman of the House Government Operations subcommittee on manpower and housing, are trying to get the Office of Management and Budget to back off its opposition to the department's performance standards for the new Jobs Training Partnership Act.

Albert A. Angrisani, the assistant secretary in charge of the program, received a letter from the OMB this week, rejecting the plan because of the red tape it would generate. Others are convinced that it is necessary to save the new program from the abuses of its predecessor, the Comprehensive Employment and Training Act program.

Angrisani has been reluctant to criticize the OMB. But an aide to Frank called the OMB's letter to Angrisani "pitifully brief and inadequate." Frank has summoned OMB officials to "chat" at a hearing next Tuesday.