The Education Ministry has been paying a number of teachers below minimum wage

The primary teachers union says hundreds who are in their first year of teaching, are heading into Term 2 on illegal rates of pay.

The ministry's waiting for Novopay to undertake salary assessments, and in the meantime some staff are on the lowest rate, which hasn't been adjusted to take in the new minimum wage.

NZEI's Stephanie Mills says three teachers recruited from overseas are impacted.

She's referred their case to the migrant exploitation unit.

Mills says it's unacceptable for a government agency which is trying to attract more people into the profession.

The Ministry of Education says it's working with payroll to adjust the minimum wage level, and pay affected teachers what they're owed.