Former rugby boss David Moffett threatens 'traitor' Jacinda Ardern

A former top rugby boss has called Prime Minister Jacinda Ardern and Deputy Prime Minister Winston Peters "traitors", and warned he's coming to get them.

Ex-New Zealand Rugby CEO David Moffett, a member of the New Conservative Party, made the comments on Thursday after the Government announced it would support the United Nations Global Compact for Safe, Orderly and Regular Migration.

"Yes we'll see whether you 2 traitors are still smiling when we are done with you next year," he wrote on Twitter.

"Have a good break coz you're going to need it. Next year will likely be your Annus Horibilis because we are coming to get you."

The controversial pact would create a non-legally binding way of addressing why people migrate, how to protect them, how to integrate them into new countries, means of returning them home and other issues.

Mr Peters, Foreign Affairs Minister, said New Zealand will sign up after he received legal advice saying it won't affect national sovereignty.

"The Crown Law Office and the Ministry of Foreign Affairs and Trade have provided legal advice which confirms this UN cooperation framework is neither legally binding nor constraining on this country setting its own migration policies," he said.

Mr Peters said the advice was not surprising but did debunk falsehoods and misguided perceptions about the compact.

But the decision has angered Mr Moffett, who called Mr Peters and Ms Ardern "leftards".

"There are 53million people, mostly from Africa and Sth America ready to invade other countries in the name of migration. They want out of their own countries run by criminals and dictators. The same countries that the UN want us to give $billions to...... Say No NZ," he tweeted.

"You can all be guaranteed that I will not stop fighting for all Kiwis, no matter what side of politics you are on."

His tweets have been met with some criticism, with one person calling them "a tad aggressive".

"Hang on... aren't you a migrant who moved to NZ for economic / job purposes?" a commenter said.

"Pot calling kettle. If you don't like the government providing opportunities for others to have a better life, maybe you should resign and leave."