During a rally held in Tokyo on Monday, the day before the start of the latest ministerial talks in Hawaii on a Pacific trade pact, some 1,500 farmers urged the government to protect five key agricultural products.

In negotiations on the Trans-Pacific Partnership, Japan aims to keep tariffs on what it calls "sensitive" products — rice, wheat, beef and pork, dairy products and sugar — to protect domestic farmers from an influx of cheaper foreign goods.

But Toyokuni Kakurai, who is leading the political campaign for the Central Union of Agricultural Cooperatives, known as JA-Zenchu, criticized the government at the rally for not disclosing enough information about the TPP talks.

"(The negotiations) have a great deal to do with our lives, but (information) has not been disclosed. Our dissatisfaction and anxiety have reached a limit," Kakurai said.

However, Kazuhisa Shibuya, a councilor at the Cabinet Secretariat and member of the government's task force on TPP issues, told the rally that the government "has never forgotten Diet resolutions" adopted in April 2013 to protect Japan's key farm products.

JA-Zenchu has consistently opposed Japan's participation in TPP talks.

In 2010 the then government, led by the Democratic Party of Japan, expressed its intention to study whether to join the negotiations. Protest rallies have been held not only in Tokyo but also in other areas, often drawing several thousand farmers.

Ahead of the session involving ministers from all 12 TPP countries due to start Tuesday on the island of Maui, negotiation sources said Japan has proposed in bilateral talks to set a 50,000-ton zero-tariff quota for U.S. rice and gradually increase the amount to 70,000 tons over 10 years or more.

The TPP deal involves the United States, Australia, Brunei, Canada, Chile, Japan, Malaysia, Mexico, New Zealand, Peru, Singapore and Vietnam.

The parties cover some 40 percent of the global economy.