A House subcommittee considered revisions yesterday to the 6-year-old antibribery law, to meet business complaints that the law was hampering American efforts to win overseas contracts.

Supporters of the law, however, contended that the changes "would effectively gut" the law.

The changes in the Foreign Corrupt Practices Act, passed in 1977 after scandals revealed that some American companies had paid bribes to foreign officials, were offered as an amendment to the Export Administration Act being put together by the House Foreign Affairs subcommittee on international economic policy and trade.

Rep. Daniel A. Mica (D-Fla.) denied the amendment would make it easier for American businesses to pay bribes and said the changes are needed to correct defects in the original bill. But Rep. Timothy E. Wirth (D-Colo.), whose House energy and commerce subcommittee has held four days of hearing on proposed changes in the antibribery law, said the Mica amendments "would be tantamount to repeal" of the pioneering statute.

"Under the guise of promoting trade and 'clarifying' a law, the Congress is being pressured to legislate a return to the free-wheeling days of the 1970s when unscrupulous multinational corporations determined our foreign policy interests and domestic politics with millions of dollars in bribery payments," Wirth said last week in a "Dear Colleague" letter.

While the Senate approved revisions of the antibribery law last year, Wirth's subcommittee has not reported the bill to the floor. Mica's move, effectively transferring jurisdiction to the House Foreign Affairs Committee, is an attempt to break the legislative logjam.

The foreign affairs subcommittee agreed to finish consideration of Mica's amendments Wednesday morning after approving yesterday the rest of an Export Administration Act that falls far short of President Reagan's proposals to limit exports of high technology to the Soviet Union. The legislation is scheduled to be taken up Thursday by the full Foreign Affairs Committee.