A man has been taken into custody for assaulting three Mongolian men, according to Seoul police.

The suspect, who was not identified, is being questioned for his part in an assault that occurred around 3:20 a.m. on Sunday near Sinnonhyeon Station in Gangnam, Seoul.

Police believe other people took part in the attack, and are trying to track them down.

The incident follows other assaults that have taken place involving Korean and Mongolian nationals in an apparent tit-for-tat.

Early last month, it was belatedly found that a group of middle school students here had brutally assaulted their classmate in July, recording their attack on video and distributing it online.

Days after the assault was reported in the media, a Korean man was assaulted by Mongolian nationals in the country’s capital Ulaanbaatar. There was speculation that the incident had been instigated by the earlier assault on the Mongolian girl, on the grounds that the attackers assaulted the victim after asking if he was Korean.

After reports on the July incident, a rally was held in front of the Korean Embassy in Ulaanbaatar to protest.

Any link between the incidents has not been confirmed, but there has been criticism of the discrimination against foreigners and immigrants in Korea.

The National Youth Policy Institute recently released a survey on students with non-Korean backgrounds and found that 27 percent of students from foreign or mixed households have experienced discrimination.