Thousands of Japanese farmers and fishermen have rallied in Tokyo to voice opposition to Japan’s proposed participation in an expanded Asia-Pacific free trade organization.

Japanese media say more than 100 lawmakers joined Tuesday’s rally, with some 6,000 participants backing a new push to block the government from joining Trans-Pacific Partnership (TPP) negotiations without clear reasons and objectives.

Japanese debate on TPP membership has split Prime Minister Yoshihiko Noda’s ruling party, which took office in late August.

While the prime minister supports membership, opponents say the elimination of import tariffs would increase foreign competition at the same time farmers and fishermen are struggling to recover from the massive earthquake and tsunami that wrecked Japan’s northeast in March.

Proponents in Japan’s manufacturing sector argue that TPP membership will improve access to foreign markets and help the country compete with regional rivals for trade and investment.

Chile, New Zealand, Brunei and Singapore are current TPP members, while the United States, Australia, Vietnam, Malaysia and Peru are negotiating membership. Delegates have been pushing to announce an outline agreement at the Asia Pacific Economic Cooperation summit opening Saturday in Hawaii.

Japanese news reports say Mr. Noda will explain his support for TPP membership this week.