Citizens' and student groups staged sit-ins and demonstrations Thursday near the Diet to protest Japan's involvement in the likely U.S.-led military retaliation for the recent terrorist attacks in New York and Washington.

Peace activists began a sit-in outside a Diet members' office building at around 9:30 a.m., displaying signs showing their opposition to Japan's participation.

Senior group member Jun Kunii, 51, cited the war-renouncing Constitution and called on Prime Minister Junichiro Koizumi not to support retaliatory efforts. The issue should be resolved through diplomacy, Kunii said.