Police have charged a former Government minister with abusing his ex-MP perk of taxpayer-subsidised flights.

Roger McClay is to appear in the Auckland District Court next Friday to face 56 charges of obtaining or using a document to obtain a pecuniary advantage.

Police spokeswoman Noreen Hegarty would not confirm the criminal charges, citing sections of the Official Information Act that protect a person's right to a fair trial and privacy.

Mr McClay did not return phone calls.

The Weekend Herald revealed in December that the former National Party politician was being investigated for allegedly using his ex-MP perk of taxpayer-funded flights on business trips, then claiming driving mileage from charities he worked for.

Detectives executed search warrants on Mr McClay's Auckland home and seized financial records from Keep New Zealand Beautiful - of which he was the chairman - Heart Children New Zealand and World Vision.

Staff and board members were also interviewed as part of the police inquiry.

The 65-year-old allegedly invoiced the charities for the cost of driving to engagements, but took taxpayer-funded flights instead.

As a former MP elected before 1999, he is entitled to a 90 per cent subsidy for 12 domestic return flights each year.

Mr McClay resigned as Keep NZ Beautiful chairman in July to take up a position at the NZ Spinal Trust.

During his 15 years in Parliament, until 1996, he was Minister of Youth Affairs and Associate Minister of Education and Social Welfare.

He was then appointed the Commissioner for Children, and in 2005 was made a companion of the Queen's Service Order for his public service and his contribution to the welfare of children.

More recently, Mr McClay - whose son Todd is National MP for Rotorua - has worked for charities including Keep New Zealand Beautiful, World Vision and Heart Children New Zealand.

The Weekend Herald understands the Parliamentary Service, which administers MPs' travel subsidies, spoke to Keep NZ Beautiful's chief executive in December 2008.

In February last year, Glen Innes CIB detectives also interviewed him.

The new chairman of Keep NZ Beautiful, Tony Rush, declined to comment as the matter was now before the courts.

Previously, Mr Rush had said the police inquiry played no part in Mr McClay's decision to resign as chairman last July.

"Roger had indicated very early on in his last term that it was time for a change. To some extent it was a matter of timing," Mr Rush said in December.

"I feel for Roger personally. He threw himself heart and soul into the job of being chair of Keep NZ Beautiful. He believed in the organisation. He had its best interests at heart."

Representatives of World Vision and Heart Children New Zealand also declined to comment as the matter was before the courts.

Two other charitable trusts with which Mr McClay is involved - Variety, the Children's Charity, and For the Sake of Children - are not involved in the police inquiry.

1981 - 1996: National Party MP
1990 - 1996: Minister of Youth Affairs and Associate Minister of Education, Social Welfare and Pacific Island Affairs.

1998-2003: Commissioner for Children
2005: Made a companion of the Queen's Service Order
2005-2009: Chairman of Keep New Zealand Beautiful.
* Education and liaison roles with World Vision and Heart Children New Zealand