South Korean blockbuster Silmido has set a new box-office record by passing four million admissions only 15 days after its December 24 release.

The speed past that mark beats by a day the performance of The Return Of The King - which itself has passed five million admissions - and significantly exceeds the previous record for a Korean film of 23 days, shared by My Wife Is A Gangster (2001) and all-time box-office champion Friend (2001).

Directed by Kang Woo-suk, the founder of major studio Cinema Service, Silmido has enjoyed strong word of mouth, with a slight increase in admissions in its second weekend. It is currently screening on 380 of Korea's estimated 1000 screens, and has grossed $22m to date.

Local industry watchers say that the film may approach the all-time box-office record of 8.2 million admissions set by Friend in 2001. It is attracting a significant number of older viewers, in a country where most people stop going to the movies after getting married.

Silmido is based on a real-life incident from the 1970s in which 31 convicts and death row prisoners were moved in secret to a remote island, where they underwent intense training for the purpose of assassinating North Korean leader Kim Il-sung.

Co-producer Hanmac Films originally persuaded Columbia Tristar to fully finance the work in what would have been its first foray into Korean production, however when the film's budget rose to $7m - quite high by local standards - Cinema Service stepped in and took over the project.