Authorities in Japan are investigating the case of 700 foreign students at a university who have been reported missing since late 2018.

The Tokyo University of Social Welfare revealed that 700 of its foreign students – including students from Vietnam, Nepal and China – have been skipping lectures and have lost contact with the university since April 2018, VN Express reported.

The missing students have reportedly overstayed their visas and are now in the country illegally. The government has launched an investigation to locate the missing. Reports indicate that the students enrolled in the institution as researchers for the academic year 2018-2019, which is set to conclude later in March.

The missing students have since been removed from the student profile. The Justice Ministry of Japan pointed out in 2017 that a number of foreign students registered with the university were caught staying in the country illegally after their visas expired.

Vietnam sends the largest group of technical interns to Japan, with the number being recorded at about 127,000 in 2017.