Nobody will say how much was paid for it or when it purchased or what price might price might have been the previous record, but the 4th-century B.C. Greek Bronze statue purchased recently the J. Paul Jetty Museum in Malibu, Calif; may be the most expensive object d'art in the world.

Reports published in London have the life-sized athlete going for $5 million at a secret purchase last week. A museum spokeswoman said it cost less and was bought earlier. The previous record was apparently, $5 million paid by Washington's National Gallery of Art for Leonardo da Vinci's "Ginevra da 'Benci," For Greek antiquities, the previous record is thought to have been the $1 million paid by New York's Metropolitan Museum for a Greek vase in 1971.

The status was sold by Artemis Group International, an art holding company founded seven years ago by Belgian banker Baron Leon Lambert (whose mother is a Rothschild) and Briton David Carritt, an Old Masters painting expert formerly at Christie's auction house.

Eugene Thaw, member of the Artemis board of directors in New York, said yesterday Artemis had bought the bronze in 1971. "It had been in a private collection, for some time before that," Thaw said. "I don't know whose." Thaw read a statement which said, "restoration took several years as did the necessary technological and historical studies." The work was done, he said, by H. Herzer and Co. of Munich, an antiquities specialist.

Henry Geldzehler, a curator at New York's Metropolitan Museum, said he had seen photographs of the bronze and found it "magnificent." Douglas Lewis, curator of sculpture at the National Gallery, does not collect antiquities, but had heard from a friend who had seen photographs of the sculpture that it was "fabulous."

Dr. Jiri Frel, curator of antiquities at the Getty, issued a statement saying the bronze would go on display in March 1978 and that it was a work "related to Lysippos, the court sculptor of Alexander the Great."

Under the terms of J. Paul Getty's will, the museum - housed in a $17-million replica of a Pompeiian villa - got $720 million worth of Getty Oil Co. stock. It is thought that these monies are just becoming available to the museum, which is the best-endowed in the country. Its collection of antiquities - not Getty's strongest interest - is already "very strong," said Lewis, if only for its possession of the Landsdowne Hercules, wich was once owned by the Emperor Hadrian.

Its undisclosed price, said Thaw, "probably is a record for a sculpture. We haven't sold any other bronzes of this type.I don't think anybody has. It is the only 4th-century Greek bronze that has appeared on the market that could be sold. All the remaining ones are in Greece. or in the possession of the governments which found them."