Japan's embassy in Beijing says Chinese authorities have formally arrested a Japanese businessman who has been detained since March on suspicion of espionage.

Embassy officials say the formal arrest was made in mid-October. The man, who is in his 50s, has been identified as an employee of major Japanese drug maker Astellas Pharma. He has lived in China for a total of about 20 years.

Chinese security authorities detained him in Beijing in March on suspicion of violating China's criminal law and anti-espionage law. His status was changed to criminal detention last month.

It will take up to seven more months before a decision is made on whether to indict him.

Japan's Chief Cabinet Secretary Matsuno Hirokazu told reporters on Thursday that the government has confirmed the man's arrest and has been doing everything possible to support him and his family.

Matsuno said Japan has strongly urged the Chinese authorities through various channels and occasions to release the man at an early date. He said the government will continue these efforts.

The man is one of the Japanese nationals detained by China for alleged spying activities under the anti-espionage law that came into force in 2014. The scope of activities that amount to spying was expanded in a legal revision that took effect in July, raising concerns among foreign businesses operating in China.