Chief negotiators from the 12 Pacific Rim countries involved in the Trans-Pacific Partnership trade talks began discussions Monday in Singapore before a full ministerial meeting later this week where tough political decisions will come to the fore.

At the working-level meeting through Friday, top officials from the TPP members will try to thrash out thorny issues ranging from tariff elimination to intellectual property rights, before bringing them to the ministerial level.

Akira Amari, minister in charge of TPP talks, said Monday in Tokyo that Japan and the United States, the two biggest economies in the TPP, will begin bilateral working-level talks in Tokyo Tuesday in parallel with the ongoing session in Singapore, where each side will offer plans in an effort to seek progress.

"We will both play our last cards," Amari said, but he reiterated that Japan will not change its stance of retaining duties on its five "sacred" farm products of sugar, rice, wheat, beef and pork, to protect the domestic agricultural industry from a flood of inexpensive foreign products.

Tokyo and Washington have been at odds over how to deal with Japanese tariffs on farm products as the U.S.-led TPP aims in principle to abolish all tariffs. The two have not been able to find a solution for auto trade issues either.

On Saturday, Amari met with U.S. Trade Representative Michael Froman in Washington in a last-ditch effort to solve the issues, but they moved no closer.

Amari said Tokyo and Washington still remain "far apart" over how much they can concede.

The U.S. has been in conflict with emerging Asian economies such as Malaysia and Vietnam over how to deal with intellectual property rights as well as reform of state-owned firms, hampering the broader negotiations.