Murray Chandler, New Zealand's only chess Grandmaster, has donated $35,000 to the Act Party.
The donation was declared under rules requiring donations of more than $30,000 to be disclosed within 10 days of receipt under Section 210 C of the Electoral Act.
Asked about the donation, Act leader David Seymour said he did not play chess very well himself.
"But I know a white knight when I see one.
"He is an outstanding New Zealander and Act is very grateful for his generous support."