The chairman of a House conference committee yesterday accused the Reagan administration of being "wimpish" by refusing to act decisively against foreign companies that have sold sensitive military technology to Soviet Bloc nations in violation of export control laws.

Rep. Don Bonker (D-Wash.), who will head House conferees on export control portions of the trade bill, told a quartet of administration officials that their opposition to Senate-passed legislation that would ban sales in the United States by Toshiba Corp. and other companies that violated export control laws by selling technology to the Soviets goes against the president's tough foreign policy image.

Although he opposes the sanctions, Bonker said the administration has lacked a strong policy on the export control issue, and could have undercut the sanctions legislation if it had used existing laws to punish Toshiba and other companies that illegally sold high technology to the Soviets.

"This administration is known for its toughness on foreign policy and its commitment for national security," said Bonker. "It seems to me the administration is wimpish on this issue."

But Allan Wendt, the State Department's senior representative for technology transfer, argued that the sanctions voted by the Senate on July 1 would be counterproductive, while the administration's policy has persuaded two allies -- Japan and Norway -- to strengthen their export control efforts. Commerce Acting Undersecretary Paul Freedenberg said the sanctions would be "a disincentive" for other allies to adopt stronger export programs.

Wendt acknowledged after the hearing that the Senate's lopsided 95 to 2 vote in favor of the sanctions may have helped Japan and Norway to speed changes in their export control laws and enforcement procedures.

The issue arose with the disclosure this summer that Toshiba and a state-owned Norwegian arms company, Kongsberg Vaapenfabrikk, sold to the Soviet Union computerized milling machinery that allows the Russians to make their submarines quiet enough to avoid U.S. detection. Two weeks ago, a Norwegian police report found a 10-year pattern of illegal diversions to the Soviet Union by Kongsberg, working with firms in France, Italy and West Germany, as well as with Toshiba.

The legislation, pushed by Sen. Jake Garn (R-Utah), orders a two- to five-year ban on sales of products made by Toshiba and Kongsberg. It also could apply to any diversions listed in the Norwegian police reports after Jan. 1, 1980.

Administration officials at the hearing appeared surprised by the continued strength of congressional anger on the issue, especially since Toshiba and some of its American customers have waged a high-powered public relations campaign to blunt the sanctions. The administration, moreover, has gone out of its way to trumpet promises made by Japanese and Norwegians to improve their export control procedures.

Deputy Undersecretary of Defense Stephen Bryen said he expected the addition of Western European allies to the list of export control violators should serve to "de-Japanese" the issue. "A lot of it is bound up with Japan and the problem of trade with Japan," and the Norwegian report "puts it in perspective."