"The TPP was originally signed by 12 members so for the pact to come into effect with 11 countries, we need a new international agreement," Japan's chief negotiator Kazuyoshi Umemoto said.
He added that the involved parties have just agreed not to lower the level of the high-standard trade rules contained in the original treaty.
The chief negotiators will meet again in Australia in late August or early September to advance their talks on the implementation of the deal before November, when their leaders will gather for an Asia-Pacific Economic Cooperation forum summit in Vietnam.
Following a meeting of the 11 countries' trade ministers in Hanoi in May, the negotiators have the task of drawing up options to bring the pact into force at an early date and to facilitate the possible return of the US.
Japan, the largest economy among the 11, hopes to reach an agreement to change the requirements for bringing the TPP into effect without revising the content of the pact.
The TPP was signed by Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore, the US, and Vietnam, covering around 40 percent of the global economy.