Parliament is launching an inquiry into the MP who failed to declare 25 properties, after a Herald investigation.

Trusts linked to Whanganui first-term National MP Carl Bates and his family own 25 properties that are not disclosed on Parliament’s list of MPs’ property and financial interests.

Many of the properties are rentals in Whanganui, making Bates’ family one of the biggest private landlords in his electorate, the Herald revealed.

Labour Party MP and chief whip Glen Bennett has written a letter to the Parliamentary Registrar requesting an inquiry into whether Carl Bates MP has complied with his obligations to declare certain interests.

The Registrar of Pecuniary and Other Specified Interests of Members of Parliament, Sir Maarten Wevers, took a preliminary review of the request and found it was warranted.

“The registrar’s preliminary review took account of the degree of importance of the matter under inquiry; whether the matter may involve a breach of the obligations to make a return; and whether the matter is technical or trivial,” a letter from Weavers’ office said.

Bates told the Herald previously he was merely a beneficiary of the trusts and had checked he was declaring everything required of him.

Several of the trust properties are at the lower end of the Whanganui market, with rateable values (RVs) ranging from $ 160k to $ 375k.

One property, a modern three-bedroom house with a rateable value (RV) of $500,000, was recently rented out for $570 a week, providing a 6% rental return.

Further up the country is a $855k two-bedroom townhouse in Epsom, Auckland, a “modern terrace home, extending over three levels, perfectly suited for an ambitious young family, a professional couple looking for a hassle-free lifestyle, or investors”.

Under Parliamentary rules, MPs must declare their business, property and other legal interests, “thereby providing transparency and confidence in parliamentary processes and decision making”.

These declarations are recorded and published on Parliament’s Register of Pecuniary Interests. The register is overseen and published by Wevers. The pecuniary disclosure rules are ultimately set by Parliament’s Standing Orders Committee.

Bates told the Herald, “When I moved into politics, I exited my business interests to focus solely on being an MP. This included selling my businesses and moving away from involvement in a family property portfolio.

“As a discretionary beneficiary of a family trust which has an interest in a property portfolio, I have no involvement in it or its interests, as is common for family trusts.

“Upon becoming an MP, I met with the Registrar of Pecuniary Interests in advance of filing my return to ensure I would be declaring everything required of me.”