A Japanese news agency says a North Korean interpreter sought asylum through the South Korean embassy in Mongolia in August during a visit with a delegation from Pyongyang.

Citing a diplomatic source, Kyodo News reported on Saturday that the interpreter defected through the South Korean embassy in the Mongolian capital, Ulaanbaatar, in late August while traveling as part of a group led by Thae Hyong-chol, president of the North’s Academy of Social Sciences.

Though the interpreter’s affiliation and position were not disclosed, Kyodo said there is speculation about the person’s social status, considering Pyongyang’s restrictions on overseas travel.

Kyodo also said Pyongyang replaced its North Korean ambassador in Mongolia, suggesting the diplomat may have been held to account for the defection, although it is unclear if the two events were directly linked.

The news agency said South Korea’s foreign ministry, when asked about the matter, said it was not in a position to give a response.