National has shut Labour out of the Trans Pacific Partnership (TPP) process so can't accuse it of flouting the tradition of collaboration on trade negotiations, the party says.
New Zealand International Business Forum claimed Labour broke the bipartisan consensus because the party was against the trade deal.
Labour's Trade and Export Growth spokesperson David Clark said the party opposed the deal in its current form because it undermined sovereignty.
This could have been avoided if former Trade Minister Tim Groser had not ignored decades of bipartisanship on trade, he said.
"This time it appears that a lot has been done in secret that we were unaware of.
"We lay out our bottom lines to try and make it a clearer process and the government has shunned those.
"As a consequence that puts the bipartisan trade, which has always been there, under stress."
Meanwhile, Labour leader Andrew Little has made David Shearer apologise for comments he made on Thursday about personally supporting the TPP agreement.
Mr Little said Mr Shearer agreed the comment was careless and did not represent the decision made by the caucus.
Mr Shearer has also apologised to his colleagues.