The National party has put forward its own legislation to create the Kermadec Ocean Sanctuary, a move which could drive a wedge between parties in the coalition government.
Nelson MP Nick Smith has lodged a member's bill to ban all mining and fishing over 620,000km/sq around the Kermadec Islands.
The Greens have previously proposed such a sanctuary, but New Zealand First opposes it and any plans have been put on hold until a solution can be found.
Dr Smith said he rejected suggestions he was stirring trouble.
"It's gotta be bigger than simply party political gains.
"We gave it our best shot in government. To get there you need perseverance, you need to keep trying. This is National continuing to want to do the right thing for improving protection of New Zealand's ocean area."