MOSCOW, JULY 30 -- The Soviet government today charged U.S. diplomats here with instigating recent demonstrations by Crimean Tatars seeking recognition of their homeland and moved to quash the protest campaign, reportedly expelling Tatar leaders from the capital.

After a new gathering by the Tatars this morning in central Moscow, the Soviet Foreign Ministry summoned Mark Ramee, acting minister counselor at the U.S. Embassy, to receive an oral protest about alleged efforts by several U.S. diplomats "to inspire nationalistic manifestations" and "antisocial actions" by the Tatars, the state news agency Tass said.

The charges appeared to mark an abrupt toughening of the government's attitude toward the Tatars, whose three-day vigil at the Kremlin wall last week and scuffles with police in Red Square Saturday night have posed a new test of Kremlin leader Mikhail Gorbachev's tolerance of political dissent.

In an unusual action, the main news broadcast of state television tonight showed pictures of what it said was a U.S. official, embassy First Secretary Shaun Byrnes, meeting with several members of the Tatar group in a "secluded place" near a Metro station. Tass accused Byrnes of being the "permanent curator" of the protesters and said he and other diplomats were guilty of "gross interference in the affairs of the host country."

In a statement, the U.S. Embassy here scoffed at the accusations as "absurd" and said they showed that glasnost, Gorbachev's campaign for greater openness in Soviet society, "has its limits and is not understood by all here."

The embassy statementsaid, "There is nothing illegal or improper in U.S. diplomats having contacts with Soviet citizens of various groups. To think otherwise shows a fundamental misunderstanding of proper diplomatic activities."

The Soviet reports did not name other American officials allegedly involved in improper activity or say how many there were. U.S. officials said tonight that there had been no indication by Soviet officials that Byrnes would be expelled from the country.

This morning, police sought out several Tatar activists visiting here and told them to return to their homes, Tass said. Up to 800 Tatars, mostly from central Asia, have convened here to demand that their original autonomous homeland in the Crimean Peninsula be recreated. The settlement was abolished and about 250,000 Tatars were deported to Soviet Asia in 1944 because of alleged Tatar collaboration with invading German forces.

Dissident sources in Moscow said tonight that some of the 21 members of an "initiative group" leading the demonstrations had been forcibly removed from the capital and apparently sent to their homes in central Asia. Among them was Beker Umerov, one of the three Tatars shown on television allegedly meeting Byrnes.

The sources, who have closely followed the Tatars' activities, said the 21 leaders were elected Tuesday by a meeting of 862 Tatars, who also decided that older members of the protesting group should return home together with women and children. Between 400 and 500 Tatars remained in the capital today, the sources said.

Tass said that the Tatars today "staged a demonstration with incendiary slogans" in Pushkin Square in the center of Moscow. Dissident sources said the police would not let the protesters stay there and directed them to Izmailovski Park, where leaders read out an appeal asking world leaders to support their cause.

Acknowledging that the Tatars were unjustly treated in the past, the Soviet government last week set up a commission, headed by President Andrei Gromyko, to study the issue. Gromyko met with a Tatar group Monday after they staged the dramatic demonstration in Red Square and demanded to meet with Gorbachev. After the meeting, during which Gromyko called on the Tatars to leave Moscow, spokesmen for the group told western journalists that they were dissatisfied with the government's response and planned to continue their campaign in the capital.

Tass linked the Tatars' renewed demonstrations today to meetings with U.S. diplomats. It said Byrnes "contrived to have a secret meeting" with three of the Tatar leaders yesterday. "It is easy to guess what their secret conversation in the dusk was about if in the morning a group of extremists tried to stage antisocial actions in Moscow streets," Tass said.

State television showed two grainy black and white photographs of the alleged meeting as an announcer pointed out what he said were the figures of Byrnes and Tatar leaders.

U.S. officials said they could not remember a previous instance in recent years in which a U.S. official had been photographed this way.