A Chinese organization has appealed to Japan's Emperor Akihito to return a 1,300 year-old stele taken from China over a century ago, state media reported.

The Honglujing Stele was "looted by Japanese soldiers early last century from northeastern China", the official Xinhua news agency said, and now sits in "virtual seclusion" in Tokyo's Imperial Palace.

The stone monument, 1.8 metres (six feet) tall and three metres wide, shows that the first king of the northeast Asian Bohai kingdom was given his title by a Chinese emperor from the Tang Dynasty (618-907), the report said.