Leaders of 13 factions kicked out of the Yamaguchi-gumi syndicate - Japan's largest yakuza group which boasts 23,000 members and associates - held the first formal meeting on Saturday in the western city of Kobe, local media reported.
The head of the Yamaken-gumi, one of the expelled factions with about 2000 members, was chosen to lead the spin-off, according to the Yomiuri Shimbun newspaper.
The rival group is expected to have a total membership of about 3000, the Yomiuri said.
Like the Italian Mafia and Chinese triads, the yakuza engage in everything from gambling, drugs and prostitution to loan sharking, protection rackets and white-collar crime.
As fears rise that the split could lead to a wave of gang violence, Japanese police last week called for nationwide vigilance, holding an emergency meeting with special officers from the country's 47 prefectures.

