After the FBI director expressed his “serious concern” over unlicensed stations that have been connected to Beijing’s influence efforts, China on Friday denied charges that it was running “police stations” on American soil and claimed that the locations were volunteer-run.

Human rights group Safeguard Defenders, located in Europe, revealed the existence of dozens of Chinese police “service stations” in major cities all over the world, including New York, in a study released in September.

FBI Director Christopher Wray told a Senate hearing on Thursday that it was “outrageous”that the Chinese government would attempt to set up a police presence in the United States, saying it “violates sovereignty and circumvents standard judicial and law enforcement cooperation processes.”

China’s Embassy in Washington acknowledged the existence of volunteer-run sites in the United States, but said they were not “police stations” or “police service centers.”