The nation's largest farm lobby and consumer groups linked to the sector staged a protest rally Tuesday in Tokyo ahead of Prime Minister Shinzo Abe's expected announcement that Japan will join the Trans-Pacific Partnership free-trade negotiations.

Abe is expected to make the announcement at a press conference Thursday or Friday after his Liberal Democratic Party, many of whose members depend on the farm vote, presents its terms to his administration.

About 4,000 people took part in the rally, according to the Central Union of Agricultural Cooperatives (JA-Zenchu), which is part of the Japan Agriculture group.