New Zealand First leader Winston Peters has defended embattled Corrections Minister Sam Lotu-Iiga, saying he is partly qualified for the job because of his ethnicity.

Lotu-Iinga, who is of Samoan descent, has come under fire recently over allegations of violence in prisons.

Peters made the comments after his keynote speech at the New Zealand First conference in Rotorua, in which he returned to well-trodden ground by taking aim at current levels of immigration.

Peters said Lotu-Iiga has a great understanding of some of the conditions and some of the psychology of prisoners in New Zealand, who happen to be Polynesian and Maori.