The head of JA-Zenchu, Japan's largest farm lobby and biggest opponent of a U.S.-led trade deal, announced his resignation a week after Prime Minister Shinzo Abe's Cabinet submitted a bill to the Diet to weaken its power.

Akira Banzai, the chairman who was re-elected in August for another three-year term, said at a news conference in Tokyo on Thursday that he will step down. His successor will be selected at the group's board meeting in August, he said.

"I decided to resign as the Cabinet was submitting the bill, marking an end of one chapter for us," Banzai said. "I want the reform of our organization to be done under the leadership of a new chairman."