China wants to invite Japan's Crown Prince Naruhito and his wife Crown Princess Masako to the opening ceremony of the Beijing Olympics in 2008, a Japanese newspaper said on Friday.

The move would be the latest in a series of efforts by the Asian neighbours to improve bilateral ties, beset by disagreements over wartime history, territorial disputes and competition for natural resources.

Chinese officials have already begun making informal contacts with the Japanese government about the invitation, the Yomiuri Shimbun said.

If the visit comes about, it will be the first official trip to China by members of Japan's imperial family since Emperor Akihito and Empress Michiko visited in 1992, the Yomiuri said.

The Japanese government has reacted cautiously to the approaches, the paper said.

"I've seen the report," Japan's top government spokesman Yasuhisa Shiozaki said on Friday. "There has been no official invitation extended by the Chinese government," he added.

Relations between Japan and China deteriorated to their coldest in decades under former Prime Minister Junichiro Koizumi, partly due to his visits to a Tokyo war shrine critics see as a symbol of Japan's wartime militarism.

His successor, Shinzo Abe, moved swiftly to try to repair ties and Chinese Prime Minister Wen Jiabao is scheduled to visit Tokyo in April, in the first official visit by a Chinese leader for more than six years.

"There seem to be various exchanges at unofficial functions regarding attendance by a Japanese dignitary at the opening ceremony of the Beijing Olympics," Shiozaki told reporters in Tokyo.

"It is not at a stage where the Japanese government can comment," he said.

Masako has spent the past few years out of the public eye, suffering from a stress-related mental disorder