A Norwegian man appeared in an Oslo court Tuesday to hear charges of allegedly spying for China, according to Norway’s secret service.

“We are in an initial phase. Therefore, we are rather tight-lipped now. We are not going to give many details in the case,” said Thomas Blom, a spokesperson for the agency’s counter-espionage unit.

The unidentified man, described only as a “well known” suspect, was arrested Monday at Oslo’s Gardermoen Airport upon returning from a trip to China, according to officials, who said he’ll be detained for a minimum of four weeks.

Blom said the closed-door trial is based on “attempted” efforts at espionage on behalf of Beijing, and that “data-carrying devices” were “particularly relevant” as evidence in the case.

If found guilty, the suspect could face up to 10 years in jail.

Marius Dietrichson, the lawyer representing the suspect, said that the man will plead not guilty.

The arrest is the latest development in Oslo’s strained relations with Beijing, which were hampered by the Oslo-based Nobel Peace Prize committee’s 2010 decision to award a prize to the late imprisoned Chinese dissident Liu Xiaobo — something over which the Norwegian government has no control.

China subsequently suspended a trade deal and limited Norwegian salmon imports.