MOSCOW, FEB. 15 -- A constitutional watchdog committee today sharply criticized a recent decree by President Mikhail Gorbachev authorizing joint army and police patrols in Soviet cities to prevent social unrest.

The statement by the Constitutional Compliance Committee, which was established last year by the Supreme Soviet to adjudicate constitutional disputes between the country's 15 republics and the Kremlin, represented a parliamentary challenge to central Soviet authorities. It followed a formal complaint by the parliament of the giant Russian Republic about the patrols, which are now operating in about 450 cities across the country.

The committee, which is headed by a respected lawyer and legislator, Sergei Alexeyev, gradually has been asserting its independence from Kremlin leaders over the past six months.

Last year, it struck down a presidential decree banning political demonstrations in the center of Moscow, a move that allowed radicals to organize several huge rallies right next to the Kremlin.

However, because Soviet parliamentary institutions are so young, it is unclear what genuine effect the latest challenge will have on Gorbachev's patrols policy.

By issuing a statement criticizing the establishment of joint patrols, the committee appears to be attempting to give Gorbachev time to revise his decree or seek additional powers from parliament before a formal ruling is made. At a news conference here today, Alexeyev said the committee would not make any formal ruling on the matter until its next regular session.

The committee's action effectively makes it more difficult for Gorbachev to use the army to quell domestic political unrest without formally declaring a state of emergency. It also amounts to an unambiguous condemnation of last month's storming by Soviet paratroops of television facilities in the Lithuanian capital, Vilnius, a move carried out in the name of a mysterious, pro-Kremlin "Committee for National Salvation."

Alexeyev, who describes himself as a social democrat, described the dramatic events in the Baltic republics as "a catalyst for the public uproar over the use of soldiers to protect public order." At least 19 people were killed and more than 100 injured when soldiers and Interior Ministry commandos loyal to the Kremlin stormed public buildings in Lithuania and Latvia.

The establishment of joint army-police patrols was authorized in a decree signed by the ministers of defense and the interior last Dec. 29 and subsequently endorsed by Gorbachev. The original decree said the patrols would be equipped with armored personnel carriers and rifles, provisions that later were suspended as a result of popular protests.

The action by Soviet security forces in the Baltic states also was criticized sharply by members of a U.S. congressional delegation -- which has just completed a five-day fact-finding mission to the region -- during a meeting with the chairman of the Supreme Soviet's Chamber of Nationalities, Rafik Nishanov. The chairman of the delegation, Rep. Steny Hoyer (D-Md.), told a news conference that the Kremlin risks returning to its totalitarian past if it tries to hold onto the Baltic republics by force.

"We told Nishanov that we believe that the only way to maintain {the late dictator Joseph} Stalin's borders would be to adopt Stalin's tyranny," said Hoyer, speaking in the Russian parliament after a meeting with Boris Yeltsin, president of the Russian Republic.

In an apparent indication of Soviet displeasure over Western criticism of the military crackdown in the Baltic states, Soviet officials withdrew permission for the congressional delegation to hold its news conference in the Soviet Foreign Ministry press center. Gorbachev also turned down a request to meet with the congressmen, without giving a reason.