The latest round, which will last through March 13, brings together about 600 delegates from 11 members: the United States, Canada, Mexico, Australia, Brunei, Chile, Malaysia, New Zealand, Peru, Singapore and Vietnam.
They have a combined gross domestic product that exceeds $21 trillion.
At the previous round in December in Auckland, the Office of U.S. Trade Representative said the negotiators for the free-trade agreement announced "further solid steps."
The office said on its website the negotiators "reaffirmed their mutual priority of concluding a state-of-the-art, comprehensive agreement as quickly as possible and of smoothly integrating the newest members, Canada and Mexico, into the negotiations."
It said the participation of Canada and Mexico, the two largest trading partners of the United States, "adds significantly to the economic importance of the agreement as well as to establishing TPP as the most promising pathway to promote regional economic integration and to support the creation and retention of U.S. jobs."
At the end of the New Zealand round, it was agreed that prior to the start of the Singapore talks, the negotiators would address issues in such areas as customs, telecommunications and technical barriers to trade. Through the TPP, U.S. stakeholders want to enhance their competitiveness in the 21st century and support the expansion of U.S. exports, officials have said.
Kyodo News said delegates in Singapore want to strike a deal before the end of this year. Other issues to be negotiated include competition policy, e-commerce, environment, services, investment, government procurement, intellectual property rights, market access and labor.