Officers have detained a leading North Korean defector, known as enemy zero, to prevent him from taking part in the airlift operation to promote the Seth Rogen film, which centres on the assassination of North Korean leader Kim Jong-Un.

Park Sang-hak, who defected in 1998, was close to 10 miles (16 kilometres) from the border that separates the two Koreas when police officials pulled over his trucks filled with 2,000 DVD and USB copies of the movie, plus American music and western propaganda, which was intended for delivery to North Korea via hydrogen balloons.

Forbidden from even retrieving their cargo, the activists stood holding a sign that read, "Let's bring down the hereditary dictatorship" as TV cameras arrived on the scene.

The Interview sparked an international incident between the U.S. and North Korea last year (14), when Sony Pictures, the film studio behind the release, was hacked by cyberterrorists, who threatened to leak private documents unless the film was pulled from cinemas.

Sony bosses initially agreed, but the film hit independent theatres and online streaming sites on Christmas Day (25Dec14).

Thor Halvorssen, the human rights activist behind the plan to drop DVD copies of the film into North Korea, insists he still plans to carry out the stunt, telling reporters at the rally, "The sun rises tomorrow. And we have a plan."