The processing of 21 student visas has been suspended at four private training establishments by Immigration New Zealand.
The agency says the National Institute of Studies, EDENZ Colleges, Aotearoa Tertiary Institute and the New Zealand School of Business and Government failed to comply with their obligations in respect to international students.
The breaches include misleading or poorly maintained attendance records and fee discrepancies.
Immigration general manager Peter Elms said some individuals are also being investigated for suspected immigration fraud and they could face a lengthy prison sentence.
The investigation is expected to take up to two months.
The New Zealand Qualifications Authority has also issued compliance notice to the institutes because of discrepancies over student fees.
However, more than 800 students enrolled at the schools are not affected.
