China and the United States have extended a key intergovernmental agreement on combating the theft of and illegal trade in cultural relics, the National Administration of Cultural Heritage announced on Thursday.

The memorandum of understanding, which was first signed on Jan 14, 2009, concerns US import restrictions on "archaeological materials ... representing China's cultural heritage from the Paleolithic period (c.75,000 BC) through the end of the Tang Dynasty (618-907), and monumental sculpture and wall art at least 250 years old".

The agreement, which is dynamic in nature, was renewed twice before — in 2014 and 2019. Its objective is to act in accordance with UNESCO's 1970 Convention on the Means of Prohibiting and Preventing the Illicit Import, Export and Transfer of Ownership of Cultural Property.

Chinese monumental sculptures and wall art, such as Buddhist rock carvings and frescoes, that were created before 1774 — which was during the reign of Emperor Qianlong (1736-96) of the Qing Dynasty (1644-1911) — are restricted for import in the US starting in 2024, according to the agreement.

The extended agreement has been approved by the State Council, China's Cabinet, and confirmed by an exchange of notes between the two countries. It will be valid for five years starting on Sunday.

The signed document will act as a guideline for US Customs and Border Protection officers to restrict the import of certain archaeological materials from China.

Between 2009 and 2023, a total of 504 Chinese cultural relics were returned from the US to China on 15 occasions, thanks to bilateral judicial cooperation based on this agreement document.

In February 2019, the US returned 361 Chinese cultural relics to China on one occasion. They were seized by the Federal Bureau of Investigation during a 2014 raid at a farm in Indiana. This case remains the largest single repatriation of Chinese relics from the US.

The most recent repatriation occurred in May. Two exquisite panels of Chinese stone funeral beds, which are believed to be from between the fourth and seventh centuries, were returned to China.

The panels were seized last year by the Manhattan District Attorney's Office and US Homeland Security Investigations as part of solving a criminal case.

From September to early this month, the two relics were also exhibited at the Palace Museum in Beijing.

The National Administration of Cultural Heritage issued a statement on Thursday saying that the extension of the agreement is a practical step toward expanding cultural communication and cooperation between China and the US, as underlined by the two countries' heads of state.

"China and the United States have joined hands in cultural heritage (protection)," the statement said. "That set an example of safeguarding shared wealth of humanity through joint global crackdown on theft, clandestine excavation and illicit import and export of cultural properties."

China had signed similar intergovernmental agreements with 25 other countries by the end of 2023.