WELLINGTON • A controversy over a decision to grant citizenship to Mr Peter Thiel, a billionaire tech tycoon and adviser to US President Donald Trump, even though he did not meet normal residency requirements, has continued to simmer.

There is now a call for both the ruling centre-right National Party government and the Labour opposition to stop the finger-pointing.

"It would be nice if National and Labour stopped trying to blame each other for this particular deal and, instead, came to common agreement on ending corporate welfare," Dr Eric Crampton, an economist and head of research for pro-market think-tank New Zealand Initiative, was quoted as saying by The New Zealand Herald yesterday.

Dr Crampton had previously defended the government's granting of citizenship to Mr Thiel, saying it was a "bet worth making at the time, and one that should not be regretted in retrospect".

However, he has now said that going into business with Mr Thiel was a gamble the government should not have taken.

This followed revelations that the German-born billionaire, who is based in California, exercised a buyout option in his partnership with the publicly funded New Zealand Venture Investment Fund (NZVIF) - a move that netted the PayPal founder NZ$24 million (S$24.5 million) in profits while leaving NZVIF barely breaking even, despite both parties bearing equal risk of loss.

Mr Thiel's citizenship has sparked a heated debate among politicians and in the media, with migration fast becoming a main issue ahead of a Sept 23 election in New Zealand.