National leader Simon Bridges has said there was "nothing inappropriate" about $24,000 worth of donations wrongfully recorded as donations for him, when they were actually for the party.
Earlier this year, Bridges received two donations – one of $10,000 from Cathedral Club and another of $14,000 from Cubro Ltd.
But, according to a National Party spokesman, the donations were for the party, not Bridges.
"In the process of preparing both the local candidate and party returns, as required by the Electoral Act, two donations were incorrectly attributed to Mr Bridges candidate return by the local Tauranga Electorate Committee."
The error was discovered soon after lodging the candidate return, and the Electoral Commission was contacted immediately to seek advice, the spokesman said.
"Acting on that advice Mr Bridges' candidate return was amended, and then re-submitted to the Electoral Commission for publication.
"The National Party's complete donation return is independently and comprehensively audited."
He said the two donations were "completely unrelated to each other".
Speaking to the AM Show, Bridges downplayed the mistake.
"This is very straightforward – there is party and there is candidate, these [returns] were wrongly filed as candidate, they shouldn't have been and then they were refilled as party, it's as simple as that."
He said it was a "local person who was in charge of these things" who accidentally filed the donations into the wrong place.
"There has been nothing inappropriate there. It was a mistake," he said, adding that it was corrected "very quickly" after National received advice from the Electoral Commission.
Bridges wouldn't go into detail about what the Cathedral Club was but did say Cubro was a healthcare business in Tauranga.
According to the Electoral Commission, "Party secretaries must take all reasonable steps to keep records of all party donations received [including donations of less than $15,000]".