Faced with the threat of losing access to American technology, Austria has decided to tighten its export controls to stem the flow of sensitive goods to East Bloc countries.

The Austrian government has secured the cooperation of opposition parties in passing legislation that will impose fines and jail terms on persons and companies involved in transferring strategic western products to Eastern Europe.

Reagan administration officials often complain that lax customs patrols and a postwar tradition of serving as a neutral gateway for East-West trade have turned Austria into a bargain warehouse for Soviet Bloc countries eager to acquire restricted high-technology equipment that originates in the United States.

The exasperation with Austria's role as a conduit for classified U.S. goods to the East has grown so acute in recent months that Vienna still could wind up on a blacklist blocking its access to U.S. strategic products unless it offers satisfactory assurances that such items will not be shipped on to undesirable destinations.

In January, new export regulations will empower the U.S. Commerce Department to grant distribution licenses for sensitive goods bound for neutral nations such as Austria, Switzerland and Sweden, only if the effectiveness of their export controls has won approval in Washington.

European NATO allies and Japan already cooperate with the United States in policing traffic of strategic goods through the Paris-based Coordinating Committee, which devises lists by unanimous consent of products banned from export to the Soviet Bloc.

Austria has balked in the past at toughening export restrictions because of a reluctance to accept any extraterritorial provisions that might call into question its sovereign neutrality.

Government and business circles also have sought to avoid adopting any measures that might jeopardize the country's profitable commerce with Eastern Europe, which accounts for 12 percent of the country's total annual trade.

But the danger that Austria could be deprived of critical U.S. technology at a time when the country is straining to revive its economy by modernizing industry has goaded the center-left coalition of Chancellor Fred Sinowatz into taking urgent action.

The process has been accelerated by a more amenable Cabinet that includes Foreign Minister Leopold Gratz, who is described by diplomats here as "much more Atlanticist" in his thinking than his predecessor, Erwin Lanc, a holdover from Bruno Kreisky's days in power.

The new legislation, which Gratz insists is "an autonomous Austrian solution" sponsored by all political parties, will assure U.S. suppliers that Austrian traders who seek to divert American technology to the Soviet Bloc will be prosecuted more stringently.

Under the amended trade law, the Austrian Trade Ministry will issue import certificates to companies buying products involving controlled foreign technology. These permits will incorporate any export restrictions from the originating country stipulating that such goods must not be sent to an unauthorized third party.

This method will bring reexport controls within the domain of Austrian law, thus resolving the delicate issue of national sovereignty that often has resulted in Austrian officials refusing to cooperate with U.S. customs authorities.

However, Austrian Foreign Ministry officials stress that such controls will apply only to sensitive foreign imports and not to any locally produced items.

"This law does not apply to Austrian technology," explained Thomas Klestil, Austria's ambassador to the United States, in a luncheon Wednesday with American reporters in Washington. "We are free to export our goods to whomever we want. This has been made clear."

It is this kind of ambiguity about the origin of hybrid technology, especially in the realm of computer software, that could raise future problems between Washington and Vienna over exports to the Soviet Bloc in spite of Austria's latest efforts to appease U.S. criticism.

The new trade law will impose harsher penalties on firms or businesses that break the export restrictions imposed by foreign suppliers. Violators will be subject to as much as two years in prison and fines of one year's worth of income up to a maximum of $50,000.

U.S. officials contend that until now Austrian sanctions scarcely amounted to a benign slap on the hand. The only punishment facing companies that abused trade controls was the possible rejection of a future import license, although this penalty was rarely invoked.

U.S. officials said they hope the new trade law, once it comes into effect next month, will provide a more rigorous system for preventing the leakage of classified technology from the U.S. to the East. But some remain skeptical, because earlier promises of better enforcement were never fulfilled.

This time Austria also has vowed to increase the number of customs agents and encourage them to collaborate more intensively with their American counterparts.

Klestil has asked the State Department and other U.S. government bodies for their assessment of Austria's new trade law and claims to have received "a very, very positive response."

After years of troubled relations with Washington over the issue of technology exports, Klestil said he hopes that they "should not have any trouble at all" when the stricter U.S. export regulations are introduced next year.