Sotheby's, the international art auctioneers, said the 1987-1988 art auction season was its best ever, with worldwide sales totaling $1.548 billion.

Sotheby's said the sales figure, which covers the traditional auction season from September 1987 through August 1988 and includes projected sales for the last six weeks, represents a 21 percent increase over the previous season's sales.The auction house said sales for the first six months of 1988 amounted to $881.7 million, up 17 percent from $752.4 million in the comparable period a year earlier.

"Sotheby's 1987-1988 auction season has been an outstanding period for the company and for the auction world," said Michael Ainslie, president and chief executive of Sotheby's Holdings Inc., parent of the auction house.

"The stock market decline of October 1987 had little immediate effect on the international art auction market, and in 1988 the art auction market has moved into its strongest period in history," Ainslie said.

In the latest season alone, Sotheby's sold 10 works for over $5 million apiece and 104 for more than $1 million each. The season's sales included two of the three most expensive paintings ever sold at auction: Vincent van Gogh's "Irises" for $53.9 million and Claude Monet's "Dans La Prairie" for $24.3 million.

Among other firsts, the season included the first international art auction held in the Soviet Union and the first sale conducted by a Western auction house in China.