MOSCOW, JUNE 5 -- Charles Z. Wick, director of the U.S. Information Agency, today cut short a stormy encounter with the head of a Soviet news agency whom he later accused of airing "polemical, Cold War, Stalinist" views.

Wick, concluding a week-long visit to the Soviet Union, told a press conference that he had "truncated" the meeting with Valentin Falin, director of the Novosti news agency. He said he left the meeting 40 minutes before it was scheduled to end after Falin accused the United States of causing epidemics in Nicaragua and Cuba.

The dispute began when Falin defended a Novosti news report that charged the United States with developing a new "ethnic weapon" that singles blacks out as victims.

Wick said the meeting with Falin was an exception to an otherwise productive, cordial round of talks with Soviet officials. After more than four hours with Alexander Yakovlev, a key adviser to Soviet leader Mikhail Gorbachev and secretary of the Central Committee, Wick said the two sides agreed to increase U.S.-Soviet cultural exchanges.

The USIA director said he welcomed the Soviet decision to stop jamming Voice of America broadcasts to the Soviet Union, which took effect late last month.

He denied that any deal had been struck to allow the Soviets to broadcast Radio Moscow programs on a U.S. medium-wave frequency from Cuba.

Since late last month, Radio Moscow programs have been beamed at the United States via a Cuban radio station, which Washington charges is illegally interfering with assigned radio frequencies. A protest was delivered to the Soviet Embassy on May 29, Wick said.

The Soviet Union has complained that it does not have access to a broad audience of American listeners because few Americans own short-wave radios. Wick said he told the Soviets that he would assist them in finding U.S. radio networks willing to broadcast Soviet programs, but only if U.S. programs could be broadcast on medium-wave here.