Kremlin Tightens Grip on Lithuania : Secession: Diplomats must leave. Journalists are barred. Moscow’s police spread throughout the republic.

Police and prosecutors loyal to Moscow spread throughout Lithuania on Friday and the leader of the breakaway Baltic republic accused Soviet President Mikhail S. Gorbachev of waging “psychological war” as the Kremlin bore down hard to halt Lithuania’s bid for independence.

As tensions mounted, the Soviet government ordered U.S. and other foreign diplomats here to leave, giving two American diplomats now in the city 12 hours to depart. The diplomats, based at the U.S. Consulate General in Leningrad, said they would leave as soon as travel arrangements could be made.

Twelve days after Lithuania’s legislature voted overwhelmingly for independence, the Kremlin’s grip tightened immensely, with the Soviet Interior Ministry, which handles law enforcement, beefing up local units and the KGB recalling reservists for its border guard and dispatching additional troops and equipment to the frontier.

Before dawn today, a column of almost 100 military vehicles rolled through the center of the Lithuanian capital, the Associated Press reported. The convoy moved along the main highway through the heart of Vilnius in the early morning darkness without stopping, the news service said.

The official news agency Tass spoke direly of the Lithuanian government provoking “anarchy in all its forms” by its recent actions, and a KGB general warned of possible North Atlantic Treaty Organization action to exploit the disorder. Such official talk has frequently been employed by the Kremlin leadership to prepare the nation for major actions or shifts in policy.

“We are under constant pressure from outside . . . (and) in Lithuania itself, in the form of a foreign army,” Lithuanian President Vytautas Landsbergis declared. “The size of that army keeps growing. It is openly demonstrating that it is armed and very strong and ready for anything.”

Soviet military helicopters hovered over this city of 579,000 people, dropping Russian-language leaflets giving the text of a Wednesday directive from Gorbachev condemning the secession as illegal and decreeing measures to reassert Moscow’s control.

Visa-free travel between Lithuania and neighboring Poland was suspended, and the Soviet government ordered steps taken to bar entry to journalists and people “inclined to unlawful actions,” effectively increasing the isolation of this Ireland-sized republic as it faces the might of the Soviet government.

The Interior Ministry, in a dispatch carried by Tass, indicated that units loyal to Moscow are now deployed throughout Lithuania, from the Polish frontier to the border with the republics of Byelorussia and Latvia.

“Steps have been taken to strengthen the protection of important federal installations,” the ministry said. “Patrols, stationary posts and mobile transport inspection groups are operating on all motor-ways, including in border areas.”

The Moscow-based ministry said its officials are overseeing confiscation of firearms in line with Gorbachev’s directive, the first real use of his expanded powers as Soviet president, a new government post he was elected to last week.

The Interior Ministry said it sent in “groups” of officials but did not reveal their number or functions. As well as overseeing the nation’s fight against crime, prisons and other police matters, the ministry has its own armed force of about 340,000 men.

Lt. Gen. Valentin K. Gaponenko of the KGB border guard told Tass that local reserves have been mobilized to reinforce detachments patrolling the Lithuanian stretch of the Soviet-Polish border. The Interfax News Agency said a special squad of senior Soviet prosecutors arrived in Vilnius on Friday.

The sweep of these concerted actions showed Gorbachev’s Kremlin moving resolutely to take command of key sectors while allowing Landsbergis and his allies, at least for a time, to remain in power, even if their orders will now go unheeded by many officials.

The Lithuanian president, in his remarks to the republic’s Supreme Council, or Parliament, said the Soviet military was reinforcing local garrisons, as it moved from economic measures against secession to a show of force.

“We are seeing maneuvers and new units being transferred here, and how they are demonstrating their arms and their presence,” Landsbergis said. “We see this as part of a psychological war--a certain kind of psychological warfare is being waged against Lithuania.”

Prime Minister Kazimiera Prunskiene had complained Thursday of increased activity by the 30,000 Soviet soldiers that she estimated are stationed in the republic, and demanded an explanation from Gorbachev.

Asked to comment on Landsbergis’ charge that new detachments were being sent, an official in the Soviet Defense Ministry’s external relations department in Moscow said, “We have no such information.”

Soviet authorities barred journalists from going to Lithuania on Friday because “the situation is changing there,” a Foreign Ministry official told representatives of the British news agency Reuters in Moscow on Friday night. Dozens of foreign correspondents were drawn to Vilnius to cover the republic’s dramatic March 11 independence proclamation and the escalating crisis with Moscow.

Reporters already in Vilnius were apparently unaffected by the new ruling, which springs from Gorbachev’s directives on Wednesday ordering tighter controls on who is allowed to enter Lithuania.

The Soviet president also gave Lithuanians seven days to surrender their firearms, or have them confiscated. On Thursday, he instructed Landsbergis to stop Lithuanians from signing up for volunteer groups designed to replace the KGB border guard and Soviet police, and gave him until today to report on what has been done.

Tass said Friday night that 5,500 firearms had been seized or handed in over the last two days. However, the Soviet television news program Vremya estimated that there is a total of about 30,000 firearms registered in the republic.

Scattered acts of defiance were reported Friday. In Kaunas, a reserve lieutenant colonel who heads the local branch of a paramilitary organization that prepares young men for the army refused to hand over his arsenal. Military units intervened to seize 873 firearms and over a half-million cartridges, Tass said.

In Yonova, 30 paratroopers commanded by a general surrounded a shooting range and demanded that all weapons be surrendered. The Lithuanians refused, and negotiations were still going on Friday night, said Edvard Tuskenis of the government Information Bureau.

Moscow authorities acted in force to oppose decisions taken by the secession government, with Tass reporting that Lithuania’s negation of Soviet laws “cannot but provoke anarchy in all its forms.”

Acting Soviet Prosecutor General Alexei Vasiliev rejected as illegal the appointment Thursday of a new top prosecutor, noting that the constitution empowers only the prosecutor general in Moscow to make such an appointment. Gostelradio, the Soviet broadcasting authority, said Lithuania had no right to dissolve its local branch.

But the most worrisome comment for average Soviet citizens were those of Gaponenko, the KGB border guard chief, who said he couldn’t rule out the possibility that “the adversary might use the unstable situation and attempt some sort of action on the state border of the U.S.S.R.”

“In recent days, warships of member countries of NATO have been observed” off the Lithuanian shore, he told Tass.

The Lithuanian government Information Bureau said in a statement Friday that it had become increasingly evident that the Soviet Union is preparing to use force to crush the secession attempt.

“We turn with hope to the nations of the world, governments of nation-states and all people of goodwill, to request that protests be made against the possible use of any form of coercion and violence against a peaceful member state of the world community, Lithuania, and its citizens,” said the statement, which repeated a plea made by Landsbergis.

In the afternoon, helicopters dropping leaflets flew close to the vast, brightly lit hall where the Supreme Council now meets. Several deputies chuckled grimly at the din, symbol of Moscow’s continuing power over the would-be independent state.

As control over much of Lithuanian life seemingly slipped through their fingers, the lawmakers gathered in their gold-toned chamber to choose 18 ministers to take the reins of government. One would be a defense minister, but without an army.

The legislature was to meet through the night to quiz candidates for the ministerial jobs and make appointments. Landsbergis said the haste was necessary so that Lithuania could present a united front and “speak to the world also in the name of an already confirmed Council of Ministers.”

The republican president met Friday night with three Soviet generals to fix the status of at least 840 young Lithuanian men who have recently deserted from the Soviet Army.

Schrader, a free-lance journalist, reported from Vilnius, and Times staff writer Dahlburg reported from Moscow.