The J. Paul Getty Museum in Malibu has removed its prized Greek "Kouros" for study because of new doubts about the authenticity of the statue.

The 6-foot-8-tall marble sculpture of a young man, thought to date from the sixth century BC, is one of the museum's three most celebrated Greek antiquities, along with a monumental marble "Aphrodite" and a bronze "Victorious Athlete."The museum, located off the western edge of Los Angeles by the Pacific Ocean, purchased the "Kouros" in 1985 after 14 months of study and put it on view in 1986 after additional study and conservation at the Getty. But a recent discovery of a marble torso that is generally regarded as a forgery or a modern copy has raised new questions about the Getty statue.

The torso, which came to the museum's attention in April, depicts only part of a male nude figure and it differs in surface and general appearance, but it is made of similar marble, "possibly from the same quarry" and it contains "subtle similarities of style and detail," Getty curator Marion True said in a prepared statement released late Friday afternoon.

The museum has purchased the torso from an unidentified private collector who brought it to True's attention. The "Kouros" was removed from the antiquities gallery on Friday, and the two pieces will be studied during the next several months in the museum's conservation laboratory, museum director John Walsh said in a telephone interview.

"Naturally, we will be very disappointed if our new studies lead to the conclusion that the museum's `Kour-os' is not an authentic work," Walsh said, "but it's most important that we try to discover the truth about the two statues.

"These cases arise in the field, and they occur at this museum as they do in other museums that collect antiquities," he said.

The situation would seem to be an embarrassment to the wealthy museum, which is often in the news, but Walsh said that the "Kouros" affair is more of "a puzzle, though a very prominent puzzle."

Another, far less prominent sculpture in the Getty's collection - a marble "Head of Achilles," once thought to be the work of the fourth-century B.C. Greek master Skopus - was discovered to be a modern copy two years ago.

Walsh said that the Kouros always has presented "puzzling questions" for the museum. Critics have commented on the statue's archaic-style smile and that fact that its stylized hair, eyes and hands contrast with more realistic feet and flesh around the mouth.