Environment Minister Trevor Mallard has released what he claims is a leaked copy of the National Party's environment policy.
The document, which was due to be released on Saturday, outlines the establishment of an Environmental Protection Agency.
Mr Mallard says that is surprising for a party which intends to cap government spending.
He says National has scrapped a $1 billion sustainability investment fund contained in its policy at the last election.
Mr Mallard says this is the latest in a string of embarrassing leaks.
But a National Party spokesperson says it appears a copy of the policy was simply left behind somewhere.