"We dispatched units to prepare for any sudden incidents at the hospital, where there are other patients and visitors non-related to this funeral," a police spokesman said.

Kim, who was known for arming his gang members with long sushi knives, was convicted of masterminding the stabbing murder of a nightclub manager in 1986. He was sentenced to 10 years, but the term was suspended after he was diagnosed with lung cancer.

In 1992, he was handed another 10-year jail term for setting up his own criminal syndicate, named the "Beomseobangpa" gang.

After his release, he appeared to have forsaken his gang life and began preaching against crime to young people as a reformed Christian. But a few years later he was back in prison after being convicted on bribery charges.

In 2007, he was indicted for threatening one of South Korea's top actors, Kwon Sang-woo, allegedly saying he would turn Kwon's house "into a bloodbath" if the star refused to attend a fan meeting in Japan.

He was acquitted on appeal.

Kim was admitted to Seoul National University Hospital for respiratory problems in December 2011 and remained there until his death.

Following yesterday's ceremony, his body was taken to his hometown, in South Jeolla province, for cremation.

Organised crime was widespread in South Korea during the 1960s, 1970s and 1980s, with criminal syndicates wielding considerable influence in entertainment circles, the media and politics.

An official crackdown in 1990 resulted in the incarceration of hundreds of gang members and bosses.