At a court hearing in Solna, north of Stockholm, later Wednesday, he will ask for the suspect to be taken into custody for aggravated spying.

"The man is suspected of having illegally gathered information and intelligence on people from the Uyghur community for the Chinese intelligence services," said prosecutor Mats Ljungqvist.

"The case is very sensitive and is at a preliminary stage of investigation. For this reason, I cannot provide further information at this point," he added in a statement.

The suspect was detained on Sunday according to court documents obtained by AFP, which gave his date of birth as April 8, 1967 and said that he had needed a Mandarin interpreter.

He is accused of spying on refugees, or illegal intelligence-gathering activity against individuals, the statement added.

According to Sweden's SAPO intelligence agency, these offences refer to operations targeting political opponents or other minority groups.

"This type of espionage is often carried out by authoritarian or non-democratic states," the statement added.

The Sunni Muslim Uyghurs are the main ethnic group in China's northwest Xinjiang province.

Beijing is accused of having detained more than a million Uyghurs and other Muslims as part of a campaign the UN has said could constitute "crimes against humanity".

China denies the allegations, saying its actions have allowed it to eradicate extremism in Xinjiang and promote economic development.