Auckland mayoral candidate Phil Goff has accused some South Auckland schools of failing to "do their duty" for students, disappointing principals in the region.

During a debate on Radio New Zealand this morning, candidates were questioned about diversity and segregation in Auckland, with host Guyon Espiner pointing out some schools in the south had no Pakeha children despite being "good schools".

Goff was asked if he thought the mayor had a role in promoting inclusion. He replied yes, saying his vision for Auckland was not one where some were living in gated communities while others lived in substandard accommodation.

He then waded in on education:

"My kids went to one of those South Auckland schools. It was a decile 1, Papakura High School," he said.

"I don't think it does its duty by the children that go there."

He then expanded, saying "I think we are not getting the quality we need in some of those schools. The school that I instanced was one of them. Other schools, like Aorere [College] are doing a good job."

He said a mayor could help by "speaking up" and partnering with government and industry.

Principals contacted by the Herald said they didn't agree with Goff.

Vaughan Couillault, from Papatoetoe High School, said there had been significant shifts in achievement in South Auckland in recent years.

"It's pretty hard to justify a statement saying schools are underserving our region," Couillault said.

"Once you work here you get an appreciation of the complexities. Maybe he is missing a few of the facts."

He pointed out McAuley High School had won a Prime Minister's Excellence Award last year, while other schools had featured prominently in the media for their results.

Waiuku College principal Tom Vanderlaan said the mayoral candidate shouldn't make generalisations.

"Just by making such a generalised comment he's tarring all schools with the same brush," he said.

"It's sad that comments like that tend to paint a picture of South Auckland as a whole. I'm sure there's schools in north Auckland, or in the west or in Hamilton you could say aren't performing as well. It's a shame."

Vanderlaan, who has taught in four South Auckland secondary schools, said schools in the area worked hard for their communities and there were some great examples of best practice.

He pointed out about 20 per cent of students in the region - often high achievers - left the area for other schools in the city, in part because of incorrect assumptions about decile and quality.

Principal of Southern Cross Campus in Manukau City, Robin Staples, said he was disappointed.

"We've made huge improvements not just in achievement but in retention," he said. "I'm wondering how in touch he is with South Auckland."

Staples said it was easy to "beat up on" the area.

Tangaroa College's Ngaire Ashmore said Goff was welcome to come and speak to them.

"I know about our school and our achievement and certainly believe we are punching above our weight," she said. "I'm not sure who he's referring to. There are still challenges out here but certainly schools are getting good outcomes."

Ashford said it reminded her of rhetoric about South Auckland schools from the 1980s.

Papakura High School's new principal John Rohs declined to comment.

While education was not under the remit of council or mayor generally in Auckland, it was a part of the Southern Initiative, a programme trying to transform poor urban communities by redirecting existing government welfare, education and health spending.

Goff's comments come on the same day many South Auckland schools received news of extra funding for their "at-risk students".

Education minister Hekia Parata said some schools will receive up to $100,000 extra, while others will get nothing.