Art enthusiasts paid record prices for 20th century Russian works this week, as Soviet President Mikhail S. Gorbachev visited Britain.

Sotheby's said its sale of 187 paintings, film posters, porcelain, ballet and theater designs and illustrated books drew nearly $6 million, a rec-ord for a Russain avant-garde art sale."The timing was a coincidence. We wanted to attract new buyers who were in London for the big sales of impressionist art earlier this week," said Sotheby's expert, Asya Chorley.

An unidentified buyer paid nearly $1.3 million for Alexandra Exter's 1912 "Composition (Genoa)," a visionary view of a city. The price was the highest ever paid for a 20th century Russian painting.

An anonymous telephone bidder paid $804,000 for Liubov Popova's 1918 abstract "Painterly Architectonic."

Two other Popova abstracts were bought for a total of $1.4 million by Waddington Galleries, London dealers.