WASHINGTON — Labor groups filed a complaint with a U.N. agency yesterday about a federal decision that graduate assistants at private universities do not have the right to form unions.

The AFL-CIO and the United Auto Workers complained to the International Labor Organization, an agency of the United Nations, about a July 2004 decision by the National Labor Relations Board denying teaching assistants the right to organize. The unions say that decision violates workers’ rights under international labor standards. Any ILO decision on the complaint would not overturn U.S. law.

The NLRB, dominated by President Bush appointees, ruled in 2004 that about 450 graduate teaching and research assistants at Brown University in Providence, R.I., could not be represented by the United Auto Workers because they were students, not employees.

That decision overturned the board’s unanimous ruling in 2000 that let 1,500 graduate teaching assistants join a union at New York University, a private school where teaching assistants had organized.

“NYU has gotten away with hiding behind the Bush labor board decision,” said Susan Valentine, a member of the graduate teaching assistants union at NYU. “NYU wants to position itself as an international university. They should comport themselves with international labor standards.”

NYU spokesman John Beckman said the labor complaint misses the point of the NLRB ruling.

“This filing ignores the essential point that underpins the long-held view of the NLRB, reaffirmed in their 2004 decision: Graduate assistants are students, not workers,” Mr. Beckman said. “They are admitted to the university because of their academic talents as students, not hired by the university for their skills as workers.”