Some of the opponents of the Trans-Pacific Partnership are spreading misleading information, Prime Minister John Key says.
This ahead of the formal signing in Auckland on Thursday.
"We now have some TPP opponents, including Labour, resorting to deliberately misleading New Zealanders," he said at his post-cabinet press conference today.
"Opponents claim we're giving away our sovereignty and that's completely wrong - the TPP has almost identical provisions to the China free-trade agreement."
Mr Key said other countries would not be able to write New Zealand laws and the TPP didn't increase the cost of pharmaceuticals.
"The TPP is our biggest free-trade deal, successive governments have worked to get free trade with countries like the United States, Japan and Canada for 25 years," he said.
"It will create significant new trade and economic opportunities for New Zealand... it gives our exporters access to 800 million customers in 11 countries across Asia and the Pacific."