A mother and father have been arrested for allegedly beating their eight children with weapons, including sticks and electrical cord - and the woman is pregnant again.

The Tongan couple have appeared in the North Shore District Court on eight charges, including one each of wilful illtreatment likely to cause unnecessary suffering.

Their names are not suppressed but the Herald on Sunday has chosen not to name them at this stage.

The eight children, aged 1 to 14, have been taken into Child Youth and Family care and have been placed with caregivers.

CYF northern regional director Grant Bennett said his organisation and the police were alerted by a school counsellor whom one of the children had confided in.

"The eight children involved in this case have been in the care of CYF since the end of March. They are safe and well with approved caregivers," said Bennett.

"We are aware that mum is pregnant and the new child is part of our investigation and intervention."

Police allege the abuse has been going on since 2009.

The 45-year-old father is accused of beating his 14-year-old daughter with an electrical extension cord, his 7-year-old son with cricket wickets, his 5-year-old son with a Jandal and hitting his 1-year-old twin sons.

The 40-year-old woman is alleged to have beaten the 14-year-old daughter with an empty 2-litre plastic bottle.

When the Herald on Sunday visited the family's home in the North Shore suburb of Glenfield, bicycles, children's toys and rubbish littered the yard.

There was a blue tarpaulin tent in the yard, which appeared to have been used as living quarters, a portable toilet and skip - although no construction work was evident.

Domestic abuse counsellor Filipo Tipoai said there was a culture of using violence to discipline children in Pacific Island families.

"It's not just Tongan people, it's across the board with Pacific people. It's the mentality of how Pacific people perceive their history or upbringing from the island. It was okay 20 or 30 years ago and they still do it in New Zealand," he said.

Tipoai, who works for West Auckland social service The Project, said organisations like his helped explain to parents why they must change their behaviour and why they were bound by law. "It's possible; it's just a matter of explaining it in a way they understand."

The accused are to reappear in court next month.