A Rotorua opera singer is calling for Dame Kiri Te Kanawa to publicly apologise to Hayley Westenra and other "popera" stars for calling them fake singers.

Rotorua soprano Timua Brennan has come out in support of Westenra and Rotorua popera star Elizabeth Marvelly, saying they have every right to be offended and Dame Kiri should apologise to them.

"I actually feel she has put her foot in it because you cannot fake talent. I was very disappointed in her reaction to the girls and the music genre that they have chosen ... They have never claimed that they are classically trained as opera singers. They simply love their music," says Ms Brennan, who has been singing opera for almost a decade.

Dame Kiri slammed Westenra during an interview where she said popera stars are all fake singers.

"People call them up-and-coming, but they never last.

"They are the new fakes for the new generation coming through, but they can only perform with a microphone and they've basically never had any form of formal training.

"I've had a 40-year career, but these people, two or three years and they're gone," Dame Kiri had said.

Ms Brennan believed Dame Kiri had underestimated the public's affection for popera.

"She has done more harm to herself because the New Zealand public really do love Hayley and Elizabeth. They have sell out concerts."

Ms Brennan coached Marvelly when she recorded two Maori songs Tarakiihi and Hewawata for her album and said Marvelly and Westenra were not fake.

Ms Brennan said Dame Kiri had forgotten how she struggled as a young artist when she was singing cabaret.

She said Westenra had been performing for several years and while Marvelly was just starting out on the international stage, both were not "fly by (night) wonders".

Marvelly had earlier said she was not offended by Dame Kiri's comments but was surprised and did not agree with them.