Weary Herakles, the top half of a second-century marble bust depicting the mythological hero Hercules, has been returned to Turkey from a Boston museum.

Prime Minister Recep Tayyip Erdogan confirmed on Sunday that the statue had travelled to Turkey from Boston, where it had been held at that city's Museum of Fine Arts since 1981. He called the return a "goodwill gesture" on behalf of the U.S. museum.

Turkey has been campaigning for the marble's return for the past two decades, with hopes of joining it to the marble torso, which is held at the Antalya Museum in southwestern Turkey.

The Boston museum and Turkish officials signed the repatriation deal on Friday, with the agreement acknowledging that the MFA had initially acquired the object in good faith, without any knowledge of ownership issues.

"The Weary Herakles is a great work of art and we believe that it should be back in Turkey where it can be made whole once again," museum director Malcolm Rogers said in a statement. "We are pleased with this significant resolution."

Murat Suslu, Turkey's general director for cultural heritage and museums, added: "We believe that it is important that such objects should be returned to their homeland and displayed there."

Removed from Turkey in 1980

According to Turkish officials, the Hercules bust was illegally removed from an archeological dig site in Perge (located about 550 km south of Turkey's capital of Ankara) in 1980. A dealer in Frankfurt sold the piece to the Boston museum and art collectors Leon Levy and Shelby White a year later. It was first displayed in Boston in 1982.

During a loan to New York's Metropolitan Museum of Art in 1990, a scholar noted the bust's similarity to the bottom half of a marble statue on display at the Antalya Museum. Subsequent scientific testing and casts of the two pieces concluded that they were, in fact, part of the same sculpture that had broken apart.

When the museum acquired full ownership of Weary Herakles in 2004, negotiations began regarding the reunion of the two pieces.

The repatriation of the marble is one of the latest examples of historical artifacts returned to the countries or the cultures from where they originated.

On Sept. 22, Greek officials announced that the J. Paul Getty Museum of Los Angeles had agreed to return three more artifacts to Greece: an inscribed marble slab and two portions of a grave-marker relief sculpture, all dating from fifth century B.C. In recent years, the Getty has returned a number of significant, illegally excavated works to Greece.

With files from The Associated Press