ANKARA, Turkey — The Boston Museum of Fine Arts returned a piece of a Hercules statue to Turkey after two decades of negotiations, the country's prime minister said Sunday.

Turkey claimed the top of the Weary Heracles, Greek for Hercules, was stolen from an archaeological site in the Mediterranean and smuggled into the U.S. The bottom half of the statue has been displayed in Turkey.

Prime Minister Recep Tayyip Erdogan said he brought the top of the statue on his plane back home Sunday after the Boston art museum agreed to return it as a "goodwill gesture."

The 1,900-year-old marble statue shows the tired hero leaning on his club. It stands about five feet (1.5 meters) high.

The upper half was held jointly by the Museum of Fine Arts and husband-and-wife collectors Leon Levy and Shelby White of New York. The lower half is in the Antalya Museum in Turkey, along with photos of the Boston section and copies of articles about it from Turkish and American newspapers.

Turkish officials brought a cast of the bottom half to Boston in 1992 to show the pieces fit together. They said the top half of the statue was stolen in 1980 from an excavation site in Perge, northeast of the Mediterranean resort city of Antalya and 340 miles (550 kilometers) south of the capital, Ankara.

Turkey has been trying to crack down on the smuggling of Anatolian historical artifacts and is trying to retrieve those it believes were previously taken from the country.

Erdogan said Turkey has successfully forced various countries to return more than 4,000 smuggled artifacts since his government came to power in late 2002.