Japan's top government spokesperson says the country is strongly urging China to quickly release a Japanese national detained in Beijing.

The man in his 50s was detained earlier this month on suspicion of violating Chinese law. Japanese pharmaceutical maker Astellas Pharma says he is an employee of the firm.

Chief Cabinet Secretary Matsuno Hirokazu told reporters on Monday that Chinese authorities had notified Japan's government of the man's detention through a diplomatic channel.

Matsuno said Japan has requested a consular visit. He added that the government is providing all possible support, including communications with related people.