Japanese government sources say an official of the country's embassy in Beijing has met an expat detained in the Chinese capital on suspicion of espionage.

The sources say the meeting lasted for about 30 minutes, and the detained man was in good physical condition.

But it remains unknown why the employee of a major Japanese pharmaceutical firm was taken into custody by Chinese authorities last month.

The meeting came after Japan's Foreign Minister Hayashi Yoshimasa visited China and held talks with his counterpart Qin Gang on Sunday.

Hayashi also met China's top diplomat Wang Yi and Premier Li Qiang.

Hayashi protested against the detention and demanded his early release.

The government says it will ask for more meetings with the man and continue to request that China free him as soon as possible.