Archaeologists clear the upper layer of the main coffin. [Photo by Guo Jing/China Daily]

The security and protection system of China's most complete Western Han Dynasty (206 BC- 25 AD) cemetery and its surrounding areas will be upgraded, the cemetery administration bureau said.

The tomb of the "Marquis of Haihun" (Haihunhou) near Nanchang, capital of East China's Jiangxi province, is one of the few imperial tombs that has not been looted.

The marquis' palace, complex of tombs, important passages and entrances will be better protected using upgraded security systems, according to a document approved by the State Administration of Cultural Heritage.

The combined area of the palace and tombs covers about seven square kilometers, and the excavation of Haihunhou Tomb began in 2011.

Marquis Liu He was the grandson of Emperor Wu, whose reign began one of the most prosperous periods in China's history.