As part of the Reagan administration's continuing campaign to reduce leaks of critical technology to the Soviet Union, the State Department announced yesterday that it will deny visas to foreigners suspected of using their travels here to acquire restricted industrial information.

The policy will cover not only Soviet and east European visa applicants but also residents of allied countries who are believed to be diverting such information to the Warsaw Pact nations, according to William J. Schneider, undersecretary of state for security assistance, science and technology.

"We have found a considerable amount of activity where the actual purpose of a foreigner's coming to the United States has been concealed and is industrial espionage," Schneider said at a news conference. "The numbers are significant enough to be having an important impact on the military power of the Soviet Union."

In addition to denial of visas to some foreigners, he said, visas granted to others might be restricted to permit travel only in certain areas of the country. In these cases persons coming to this country to visit a factory in New York state would not be allowed "to spend the next two weeks wandering around the country."

The State Department already has ample authority to bar foreigners suspected of using their travels here to steal technical secrets, but until now the government's enforcement has been "imperfect," Schneider said.

Typical of the kind of visa applicant likely to be excluded under the new policy would be a known east European intelligence operative who poses as a "business traveler" when applying to visit the United States.

The announcement coincides with other efforts already instigated by the Reagan administration to crack down on technology leaks. The U.S. Customs Service's Operation Exodus, for example, has resulted in 229 arrests and seizure of 967 pieces of equipment since it began on Oct. 1, 1981. Under the program, Customs officials search shipments believed to contain restricted technology headed for the Soviet Union.

However, the program has been criticized by U.S. businesses, which claim that the surveillance interferes with exports and hurts American economic competitiveness. More than 2,000 shipments that have been held up by Customs officials under the Exodus program later were cleared for export, sometimes after lengthy delays.

There is also disagreement about the extent of damage to U.S. national security by the Soviet industrial espionage effort.

About two dozen cases of attempted Soviet thefts of technology over the last five years have been made public.

Nevertheless, administration officials say they are determined to continue the campaign against illegal exports. According to a 1981 CIA report, about 70 percent of all recent Soviet military advances attributable to western technology was from information that had been obtained illegally. Therefore, officials said, the emphasis should be on stopping the illegal flow, rather than on creating cumbersome new export controls.

Schneider said that the State Department has taken up with the allies the possibility of their applying similar travel controls on persons suspected of gathering militarily critical industrial secrets.