STOCKHOLM (AP) — Swedish authorities said Thursday they have charged a man with spying for China, on suspicion that he gathered information on Tibetans who had fled to Sweden.

Dorjee Gyantsan, a 49-year old Tibetan who worked for the pro-Tibetan radio station “Voice of Tibet,” was charged with “gross illegal intelligence activity” from July 2015 to February 2017, according to the charge sheet obtained by The Associated Press. If found guilty, he faces up to four years in jail.

The document said Gyantsan had “pretended to sympathize with Tibetans and Tibetan independence” to collect information.

Daniel Stenling of Sweden’s security service SAPO said Gyanstan was arrested Feb. 26. The security service said it had observed him for some time, saying he gathered information among Tibetans in Sweden then handed them over to an intelligence officer from an unidentified “foreign nation.”

Information gathered by Gyantsan included personal matters, ranging from where people lived and family relations to political activities, trips and meetings. The charge sheet said Gyantsan had traveled to neighboring Norway when exiled spiritual leader the Dalai Lama visited Oslo on March 10, 2014. Police also found that he had “several identity cards with different identities.”

“This is a very serious crime because spying affects very vulnerable people,” Prosecutor Mats Ljungqvist said, adding that refugees “must be able to feel confident that they can freely use their constitutional freedoms, for example to protest against a regime without risking persecution or other abuse.”

In Beijing, a Chinese foreign ministry spokesman said at a regular briefing that he was not aware of the case in Sweden.

Ljungqvist told Swedish broadcaster SVT the suspect had been in contact with Chinese officials in Poland and Finland. He reportedly said Gyantsan received 50,000 kronor ($6,000) on at least one occasion and had his expenses paid.

The prosecutor was not immediately available for comments. The suspect’s lawyer, Mikael Soderberg, told The Associated Press his client denies the charges.

“It is shocking news to us that China is spying on us,” Jamyang Choedon, the president of Tibetan Community in Sweden, told the AP. “This is not acceptable.”

“We have heard it is happening but now we might have a case,” Choedon said, adding that to her knowledge “this is the first time it’s been officially investigated.”

She said the Tibetan community in Sweden included some 140 people, including children. “We all know each other. I know him.”

The case comes at a time when relations between Stockholm and Beijing are tense.

China is holding a Chinese-born Swedish national on suspicion of leaking state secrets and has rebuked Sweden for demanding his release.

Hong Kong-based bookseller Gui Minhai, 53, was taken off a train by police on Jan. 20 while in the presence of two Swedish diplomats with whom he was traveling to Beijing.

Swedish Foreign Minister Margot Wallstrom has sharply questioned the rule of law in China and blasted Beijing’s “brutal” treatment of Gui. Gui sold books about Chinese leaders and Beijing has said he had “violated Chinese laws and thus must be dealt with in accordance with Chinese laws.”