BEIJING (AFP) - Chinese archaeologists have discovered the tomb of a 7th-century female politician who was one of the most powerful women in the country's ancient history, local media said on Thursday.

Shangguan Wan'er - who lived from 664 to 710 in the Tang dynasty - was a trusted aide to China's first female emperor Wu Zetian, and married to Wu's son, while having relationships with both the empress's lover and her nephew.

As a sequence of murders, coups and affairs enveloped the dynasty, Shangguan Wan'er's husband Li Xian briefly became emperor - only to be killed by his senior wife, who took power herself.

She was deposed in turn by Li Longji, who killed both her and Shangguan Wan'er.

The site was discovered near an airport in Xianyang in northern Shaanxi province and confirmed by an epitaph, China Radio International said on its website.

"The discovery of the tomb with the epitaph is of major significance in the study of the Tang Dynasty," the China Daily said, citing a historian specialising in the era, Du Wenyu.

The grave was badly damaged, suggesting a "large-scale, organised" and possibly "official destruction", Geng Qinggang, a Shaanxi-based archaeology researcher told the China News Service on Thursday.

Shangguan Wan'er was also recognised for her poetry.