Sweden has approved strict new export-control rules, becoming the last neutral European nation to regulate the shipments of American-made high-technology products to keep them from being sold to Soviet Bloc countries, a Commerce Department official said.

The new Swedish regulations were described to Reagan administration officials last week by Carl Aberg, Sweden's undersecretary of state for foreign trade, as "very forceful legislation" that allows the use of American laws to prevent leakage to Eastern European countries of technology that could help the Soviet military.

"It shows the real benefits of the administration giving export controls a high priority," said Assistant Commerce Secretary Paul Freedenberg. "We have succeeded in Europe. Now we have to turn our attention to the Pacific Rim."

Austria and Switzerland, two other neutral European nations, already have tightened their export-control laws. Along with Sweden, those nations were considered as major sources for the transshipment of American technology to Eastern Europe.

"That's where the major technology transfers to the Soviets were taking place," Freedenberg said.

Exports of high-technology products from NATO nations and Japan are regulated by a Paris-based organization, the Coordinating Committee for Multilateral Export Controls, known as COCOM.

The United States not only put diplomatic pressure on the three neutral nations until they tightened controls, but also placed the nations on a restricted list for the sale of high-technology products. This hampered their own industries' ability to acquire the kind of technology they need to remain internationally competitive. "We made it clear that, in order to get technological cooperation, they need to tighten their controls," Freedenberg said.

Aberg, the Swedish official, explained that the new rules will require companies in his country to get a permit from the nation that produced high-technology products before exporting them. If the product has passed through a chain of transactions, the Swedish companies will have to trace it back to the original country, he added.

Freedenberg said the new concerns for the United States are the fast growing nations of the Pacific Rim, especially South Korea, Singapore and Taiwan, which increasingly are producing high levels of technology with few controls on where they are sold.