Japanese Prime Minister Shinzo Abe said Friday that he hoped his team of negotiators would work to achieve Japan's national interests in the upcoming Trans-Pacific Partnership (TPP) talks starting Saturday in Singapore.

Japan's premiere said that the ongoing negotiations are "tough" and some nations are at odds regarding their national interests, but urged his TPP-related ministers to reflect the government's singular stance going forward during the talks.

Japan's chief negotiator and minister in charge of the TPP, Akira Amari, said separately that a gulf still exists between Japan and the United States, the two largest economies involved in the talks, but maintained that he would work to bridge the gap while in Singapore.

The key bilateral issues at the center of the logjam between Japan and the United States are the latter's automotive industry and Japan's agricultural sector -- negotiations, scheduled to be concluded in December last year, have been delayed due, in part, to Japan's refusal to give way on its sensitive farm sector.

Abe is under pressure from farm lobbies, including the politically powerful Central Union of Agricultural Cooperatives, to uphold tariffs on what Japan describes as its "sacred sectors," which comprise rice, wheat, beef, pork, dairy and sugar products.

Japan's refusal to make concessions has drawn the ire of other TPP-member nations, with some claiming that Japan has failed to live up to the "high ambition" of the TPP, as outlined in the 2011 Honolulu Declaration, at which U.S. President Barack Obama and other leaders pledged a complete elimination of tariffs and flexibility on the matter from all member countries going forward.

Japan however, since it entered the TPP talks, has sought to protect its fragile rice industry, for example, which sees tariffs of more than 700 percent imposed on foreign imports to protect the age-old sector from cheaper overseas competition.

Ahead of the main talks Saturday, local media reported that during a market access working group meeting the negotiators from the other 12 TPP countries bombarded the Japanese side with questions as to why it is refusing to budge on issues that could make or break the final deal.

Despite hinting in previous talks that some concessions might be possible, Japan maintains that it won't shift and that its stance has already been "enshrined" in a parliamentary resolution.

"Our stance remains unchanged that we will do our best to protect national interests," Japan's farm minister Yoshimasa Hayashi was quoted as saying.

The TPP alliances, if negotiations can be concluded this year, could potentially create a free-trade bloc that will comprise some 40 percent of the global economy, leading economists have said.