New Zealand First leader Winston Peters says any reduction in funding to the Foreign Affairs portfolio will be a serious mistake.
As Foreign Affairs Minister, Mr Peters secured a $621 million increase to the portfolio in this year's Budget.
But in issuing the pre-election economic and fiscal update on Monday, Finance Minister Michael Cullen warned funding may have to be reduced.
Mr Peters says New Zealand is already suffering the consequences of a lack of investment in this area.
He says it is short-sighted and silly for the Government to believe it can get by in a more-competitive world, without making that investment.