Government Minister Nathan Guy says he is relaxed he granted Trump campaign donor Peter Thiel New Zealand citizenship.

The American billionaire has been a New Zealand citizen since June 2011.

Mr Guy, who was the internal affairs minister at the time, said the citizenship was granted under exceptional circumstances, but followed procedures.

Mr Guy said the Department of Internal Affairs would release Mr Thiel's file later in the week.

Last week, Mr Guy told RNZ Mr Thiel was granted citizenship under a provision of the Citizenship Act stating it would be "in the public interest due to exceptional circumstances of a humanitarian or other nature", even if the person did not meet normal criteria.

Photo: AFP

Mr Thiel has sunk millions of dollars into New Zealand companies, including accounting software start-up Xero, before and after being granted citizenship.

Mr Guy said New Zealanders should be proud to have someone like Mr Thiel as a citizen and the criticism was unwarranted.

"Mr Thiel is a fantastic ambassador and salesperson for New Zealand, he's well connected in America and regardless of whether he's a supporter of the Trump administration or not he has done a lot for New Zealand."