National has been attacking Mr P' />

NZ First leader Winston Peters is threatening to reveal damaging details of National's election campaign funding.

National has been attacking Mr Peters and his MPs by saying he betrayed them and the party's supporters in exchange for a ministerial position.

Yesterday National said it would oppose new party hopping legislation resurrected as part of NZ First's support deal with Labour.

Deputy leader Gerry Brownlee said Mr Peters only wanted the law -- the Electoral (Integrity) Amendment Bill -- passed to block the departure of MPs unhappy about him accepting a ministerial position in the new Labour-led government.

"Winston Peters is very worried that his own party will cut him loose for grabbing the baubles of office."

But Mr Peters fired his own salvo back at National, claiming the party's election campaign backers gave donations in exchange for a slice of state-owned companies.

He said if National's attacks continued when he was absent from New Zealand next week, he would reveal the truth about who financed National's election campaign and what they wanted in exchange.

Mr Peters leaves for his first overseas assignment as foreign minister next week -- attending the Apec meeting in Korea.

If National "potted" away at him then, they would feel his full wrath when he returned.

"I am going to disclose their funding, their background, everything. This is an outfit the country can feel pretty pleased didn't get to be in government," Mr Peters said.

"I know those who were ... funders of the National Party campaign and what they expected of the government should there be a change. All waiting for the utilities the taxpayers and ratepayers own."

He would not disclose further details of the information, which he said had come from "responsible elements" of the National Party who were unhappy with what had taken place.