The Leader of ACT says he will complain to the Speaker of the House about an admission by Winston Peters that his lawyer received a donation of $100,000 from an ex-pat businessman.
The donation by Owen Glenn was towards the legal costs of an electoral petition in 2006.
Mr Peters had previously denied reports in The New Zealand Herald that the Monaco-based businessman gave money to New Zealand First.
However, it was confirmed on Friday when Mr Peters announced he had only just been made aware of the $100,000 donation, which was made through his lawyer Brian Henry.
At a party conference on Saturday, Mr Peters said the donation was not illegal and was not made to New Zealand First.
A Radio New Zealand political reporter says New Zealand First supporters seem to have accepted his explanation.
ACT leader Rodney Hide he will complain to the Speaker on Monday and believes she will refer it to the Privileges Committee for investigation.
Mr Peters told Morning Report that the money was to fund legal action and did not go to him personally or to his party.
Labour Party involvement suspected
Mr Glenn was the Labour Party's largest donor at the 2005 election.
Although his party has no evidence, National Party deputy leader Bill English says he believes the Labour Party had a hand in the NZ First donation.
Mr Peters' lawyer, Brian Henry, denies Labour Party president Mike Willams was involved.