Using measures ranging from a new law for foreigners staying in the Soviet Union to distinctive auto license plates for foreign correspondents and diplomats, Soviet authorities have strengthened their means of tracking and limiting unofficial contacts between Soviet citizens and foreigners.

This is the view of skeptical Western sources and some Soviets contemplating the draft of the first law on the "legal status of foreigners in the U.S.S.R." -- promulgated last week and scheduled to take effect Jan. 1 -- as well as other recent laws and regulations.

While the new laws appear to be little more than codification of longstanding regulations and administrative measures, the net result, these sources believe, will be to make it easier for authorities to intervene against unofficial interchanges and to establish ground for expelling foreigners.

Besides the draft law on resident foreigners, two other recent legal measures by the national legislature -- the Supreme Soviet, headed by President Leonid Brezhnev -- have caught the eye of activists wary of state attempts to regulate their activities.

These steps come at a time when the continuing political crises in neighboring Poland has led to jamming of Western radio stations, calls by the party for ideological vigilance, and persistent repression of even minor dissident political and religious activities here and in the provinces.

In a sense, the new foreigners' law has little to do with the way foreigners are treated: political considerations of the Kremlin leadership exercised through the state's controlling bodies determine the conditions under which non-Soviets as well as Soviets live. Because of this, Western consular officers have focused on what the law says are "responsibilities" of foreigners, rather than what it decrees about their rights.

This approach differs sharply from that of the Soviet media, which are hailing the measure as superior to capitalist countries' laws on foreigners, which "concern chiefly restrictions regulating the stay and movement of foreigners," as Central Committee spokesman Vadim Zagladin said last week.

The law confers legal status equal to that of any Soviet citizen and grants foreigners the legal right to a Soviet job, health benefits, cheap vacations and the like.

However, Western diplomats look at sections that assert that a foreigner can be expelled "if his actions contradict or threaten the interests required for state security or the preservation of general order" or that call for expulsion "if he rudely broke the rules of conduct applicable to foreign citizens in the U.S.S.R."

Their concern is that while the "rights" of foreigners may be enhanced, the sum of the law, as one Western source sid, is "an effort to put restrictions on foreigners, giving the authorities stronger grounds" to move against foreigners in the hazy areas of alleged violations of local standards of behavior, ways of life or for "sowing discord among the people," as the source put it.

It addition, other Western an Soviet surces see the promulgation of the law at this time as a warning to Soviets against contacting foreigners. This sense of concern has been raised as well by a new decree on hooliganism and another on "administrative violations" in guarded facilities, such as science institutes and military installations.

Minor hooliganism, defined as public swearing "and similar actions, violating social order and citizens' peacefulness," can be punished by a maximum of 15 days' imprisonment without appeal and without trial. While regulations to this effect have long existed, some Soviets believe this new law can easily be used if they attempt to visit the guarded compounds where foreigners are required to live and work.

Other restrictive measures include issuing correspondents bright yellow license plates and diplomats bright red ones. These replace the black-on-white plates that had been issued uniformly to vehicles registered to foreigners.

Other areas are also being tightened. Resident foreign businessmen are being denied use of hard-currency ruble coupons that all nonstudent resident foreigners with accounts at the Soviet Bank for Foreign Trade rely on for lower cost, higher quality food at the diplomatic food store.

Since late spring, Soviet customs officials have insisted the U.S. diplomats leaving for reassignment submit lists of art, folk art, antiquarian and other valuables for export inspection and approval by Soviet Culture Ministry officials.

To the outrage of some in the embassy, the State Department is understood to have ruled that diplomatic immunity from possible searches extends only to hand luggage and not to personal property. This Soviet move was made before the May incident at Dulles International Airport, when U.S. customs agents detained an Aeroflot jetliner for a sudden inspection and came up empty-handed, leaving the Soviets with a propaganda bonanza.