TRIPOLI, March 13 (Xinhua) -- The Libyan Archaeological Authority said Tuesday that a collection of stolen Greek antiquities seized in Spain will soon return to the country.

"Negotiations with the Spanish authorities on the recovery of stolen antiquities have reached an advanced stage, after six archaeological pieces stolen from the eastern Libyan city of Shahhat were identified as archaeological artifacts with unique features that only exist in Libya," Mohamed Faraj, the chief of Libyan Archaeological Authority, told Xinhua.

"We are talking about an invaluable historical treasure and parts dating back to the Greek era, especially between the 6th century and 4th century BC," he noted.

According to Faraj, the expected number of Libyan archaeological pieces recovered in Spain is 25, not 11 as previously estimated.

As early as 2016, the Libyan Ministry of Foreign Affairs said the Spanish authorities stopped the sale of 11 stolen antiquities from Libya.

The city of Shahhat, also known as Cyrene, is a historical city founded by the Greeks in the 6th century BC in eastern Libya.

Shahhat is one of the five Libyan archaeological sites listed by the United Nations Educational, Scientific, and Cultural Organization (UNESCO) as world heritage sites.