Children in the city of Kobe have been warned not to go to an annual Halloween party that is organised by the Yamaguchi-gumi, the largest and one of the most violent “yakuza” gangs in Japan.

The gang first held a street party close to its fortified headquarters in the city in 2013, with members of the normally ruthless underworld group dressing up in fancy dress and handing out sweets to local children. Last year, an estimated 1,000 children took home goody bags from the event.

Local police have expressed their concern to the city’s education authorities that the event is helping to legitimise the Yamaguchi-gumi and might even serve as a recruiting event for teenagers, the Mainichi newspaper reported.

Another fear is the possibility of violence breaking out during the event.

A splinter group of the Yamaguchi-gumi was formed in 2015, with another gang subsequently breaking away. All three crime groups are now looking to protect their local business interests - primarily in extortion, protection rackets, underground casinos, drugs and the sex industry - and there have been a number of violent clashes.