Britain would be better of trading with the Commonwealth than with Europe, Winston Peters has told a meeting in London.
"Why trade on a continental scale when you could really trade on a global scale," the NZ First leader said.
"To leave or stay in the EU is for the British people to decide, but they also have a chance to link up with the dynamic economic powerhouse of the Commonwealth."
He suggested the creation of a Commonwealth free trade area.
"In 2014 the Commonwealth produced GDP of $10.45 trillion, a massive 17 percent of gross world product," he said.
"Part of the choice the UK faces is of a Europe, divided and indebted, or trade in the developed and emerging economies of the Commonwealth."
Mr Peters was invited to London by the UK Independence Party, known as UKIP.
Despite gaining the third largest share of the vote in last year's elections, the right-wing party has only one MP and three representatives in the House of Lords.
The meeting took place at a venue in the House of Lords.
Britain votes in a referendum on June 23 to decide whether to stay in the EU or leave it.
UKIP strongly supports leaving the EU.