Federal officials yesterday rebuffed a congressional attempt to learn details of the government's negotiations last weekend with a troubled Teamsters union pension fund.

Citing the "sensitivity" of the negotiations, Labor Secretary Ray Marshall refused to appear in public session before the House Ways and Means Oversight Subcommittee.

Internal Revenue Service officials, who share jurisdiction with the Labor Department over federal pension laws, went before the subcommittee, but refused to answer any specific questions about the Teamsters Central States Pension Fund.

Dissident union members and outside groups have charged that Teamsters president Frank Fitzsimmons controlled the fund, using its $1.4 billion in assets for questionable loans to friends and business associates of Teamster leaders.

An 18-month federal investigation culminated Sunday when Fitzsimmons and three other fund trustees agreed to resign. The fund also consented to hire outside investment managers and auditors.

In return, the government dropped its threat to revoke the funds' tax exempt status and made other concessions.

Subcommittee members said the government's agreement with the Teamsters should be fully disclosed.

"Otherwise, the public is again left to ask if an insider deal was struck," said J. J. Pickle (D-Tex.).

But acting IRS Commissioner William E. Williams said at yesterday's hearing that laws protecting the confidentiality of tax information prevented him from discussing the negotiations.

After two hours of futile questioning, the annoyed congressmen agreed to decide next week whether to hold a closed hearing for Labor Department and IRS officials.

Pickle said former IRS Commissioner Donald Alexander had promised him last June 25 that IRS would take no action on the Teamster case without first informing Congress.

To his amazement, Pickle said, IRS later that same day invoked its "ultimate weapon" -- the threat to revoke the fund's exempt status.

Charles Miriani, Chicago district director of the IRS, said it was his decision to threaten the revocation and he had not informed Alexander.

Pickle was incredulous.

"You are not a doctor treating hiccups," he told Miriani. "You are making a major surgical operation -- and you made that decision yourself?"

Fitzsimmons said yesterday his resignation as a fund trustee was not a result of government pressure. He decided to resign last October, he said, to devote more time to union duties.