A digger works at the archaeological site of the three royal baths unearthed in Xi'an, Shaanxi province. [Photo by Huo Yan/China Daily]

Three royal baths have been unearthed among the ruins of an ancient city in Xi'an, Shaanxi province, archaeologists said.

They were found in August during excavations of Yueyang, the capital of the state of Qin during the Warring States Period (475-221 BC), which now forms part of the northern city's Yanliang district.

The baths are thought to have been for the exclusive use of the Qin king and his consort, with adjoining areas reserved for the royal harem.

All three are rectangular in shape, although with excavation ongoing the exact dimensions have yet to be revealed. Clay bricks engraved with patterns line their walls and floors. A well-preserved drain system has been found under one.

"This is the first royal bath of the Qin state we've found with such complete drainage," said Liu Rui, a researcher at the Chinese Academy of Sciences' Institute of Archeology.

A team of 12 diggers from both the CAS institute and the Xi'an Institute of Cultural Relics Protection has been investigating Yueyang since 2013.

It has unearthed three palaces, covering an area of 4.6 square kilometers, and identified the complex surrounding the baths as the group's core.