China's ancient capital of Xian is to build an underground line to the museum of the famed terracotta warriors, one of the nation's most prized tourist attractions, state press said Monday.

The 30-kilometre (18-mile) line will extend from Xian's city centre to the museum that houses the clay warriors that were buried more than 2,200 years ago near the tomb of China's first emperor, Qin Shihuang, Xinhua news agency said.

The army of warriors and horses of the Qin emperor was one of the most significant archaeological discoveries of the 20th century and has become a top attraction for Xian, one of China's ancient capital cities.