VILNIUS, U.S.S.R., JAN. 25 -- The Soviet Defense and Interior ministries have ordered joint army and police patrols of Moscow, the capitals of the republics and key industrial and military cities "when the situation becomes complicated," media reports said today.

The order, which goes into effect Feb. 1, could provide grounds for an extension of the current crackdown in the Baltic states to the rest of the country. Signed Dec. 29 by Defense Minister Dmitri Yazov and Interior Minister Boris Pugo, the order authorizes joint armed patrols using armored personnel carriers in the event of interference with military units or other unspecified public disturbances.

An army officer and member of the Russian republic's parliament, Sergei Yushenkov, told the independent news agency Interfax that the order resembled a state of emergency. The official evening news program "Vremya," however, said "only those with sinister purposes can draw insinuations from these measures."

The joint order appeared to be the latest in a series of decrees that have provided military and police authorities with a legal, or quasi-legal, basis for a crackdown on the rebellious republics and radical city governments. Yazov and Pugo, as well as KGB chief Vladimir Kryuchkov, have issued a series of decrees and public statements making clear that the Kremlin is prepared to use troops to preserve the union and centralized power.

Lithuanian leader Vytautas Landsbergis said, "If these {patrols} happen in Lithuania, I'm afraid we'll have yet another act of aggression," a reference to the military attack Jan. 13 on the Vilnius television tower that left at least 13 civilians dead and more than 200 wounded.

Soviet President Mikhail Gorbachev's signature was not on the order. In an interview on British television, Latvian Foreign Minister Janis Jurkans said the military is gaining power in the Kremlin and using Gorbachev only as a "symbol of democracy to get economic aid" from the West.

"Vremya" said the Dec. 29 order was announced today only to dispel "spreading rumors" about it. The evening news program said the joint order was an extension of a government decree issued in October to battle crime and harassment of military units.

Yazov and other military leaders have reacted angrily to what they have called abuse of their garrisons, especially in the Baltic states, where leaders of the republics have called for a complete military withdrawal of Soviet "occupation" troops.

Yazov and Pugo also ordered a permanent reserve for the patrols, with armed units on duty at every garrison in the country.

Pugo said on television that the situation in the Baltic states was "normalizing." The news program "Vremya" also reported that the shadowy National Salvation Committee in Lithuania had been "suspended" this week following Gorbachev's announcement that Moscow would investigate the military and police actions here and in Latvia.

Landsbergis, however, accused the Soviet military of continuing harassment and exercising arbitrary rule in Lithuania following a late-night incident Thursday in which soldiers shot and injured one man and arrested nine people, including three British journalists.

The Soviet soldiers released the journalists and two Lithuanians after they were brought to a military barracks outside Vilnius, but four Lithuanians, including members of the parliament's security guard, are still being detained. The journalists said the soldiers slapped, punched and kicked the Lithuanians during interrogation. Landsbergis said one of the security guards was "brutally beaten," suffering a cracked skull, an injured ear and bruises.

Lithuanian government officials said incidents of army harassment have been common since the attack on the television tower. Troops often pull over cars and buses and search passengers, especially at night.

"The Vilnius military garrison is becoming a mob of bandits," Landsbergis said. "Possibly, their aim is to force us to ask for assistance from the Interior Ministry in Moscow . . . so that once more Moscow seems to come to save its children."

Contradicting the three British journalists, the head of the Vilnius military garrison said the six Lithuanians were not mistreated and were investigated because one or more was suspected of firing first at the troops. Landsbergis, who spoke with the general by phone, said he told him "to stop telling fairy tales."

Although workplaces are open and public transport is working in the Baltic states, the atmosphere remains both tense and downcast.

In the Latvian capital, Riga, today, tens of thousands mourned at the public funeral of the four people killed Sunday night in a military attack on the republic's police headquarters. In the Estonian capital, Tallinn, workmen finished setting up concrete barriers around the parliament building to prevent a military attack.

In Vilnius, at the close of a special performance of Verdi's "Requiem" at the city's opera house Thursday night, the audience did not applaud but stood for a minute of silence in memory of the dead.

Officials here plan to hold a republic-wide poll on independence, but they continue to refuse to hold an official referendum, saying such a vote would admit the legality of the Soviet Union's annexation of the Baltic states in 1940.