New Zealand First leader Winston Peters' handling of donations came under sustained attack in Parliament on Tuesday.
On Friday, Mr Peters announced that his lawyer had accepted a $100,000 donation from businessman Owen Glenn to help cover his legal bills in 2006.
On Tuesday in Parliament, MPs seized on fresh newspaper allegations that New Zealand First accepted as much as $150,000 in anonymous donations from a prominent horse racing family and its companies.
But Prime Minister Helen Clark told the House that New Zealand First viewed the Dominion Post article as a smear campaign of unsubstantiated allegations.
Mr Peters, who is in Singapore for a meeting of South-East Asian foreign ministers, issued a statement rejecting the report about donations from accounts linked to the Vela family between 1999 and 2003.
Mr Peters says the accounts of New Zealand First are audited and all money received is accounted for.
A director of Vela Fisheries, Jeff Burgess, says it is a private company and refused to comment.
The Greens asked Miss Clark if Mr Peters had been involved in brokering tax breaks for the racing industry, and if he had declared any donations.
Miss Clark said Mr Peters denied the allegations and that she takes him, as an honourable member, at his word.
The National Party told Parliament Miss Clark must protect the integrity of her government in the wake of allegations against her foreign affairs minister.
National Party leader John Key used Parliament's question time to raise fresh allegations, but Miss Clark told MPs she does not expect party leaders to know the details of anonymous donations.
Miss Clark says she continues to have confidence in Mr Peters as foreign affairs minister.