"I think the TPPA is going to be a major issue not just for New Zealand, but for the US and other countries that are party to it. People are entitled to know."
Mr Little said it would also be inappropriate to hold a signing ceremony for the deal two days before New Zealand's Waitangi Day.
"Our national day is a day that we celebrate our national identity and national sovereignty, and this is an agreement that potentially compromises our sovereignty."