White supremacists sparked armed police to surround a New Zealand courthouse when depositions into the murder of a Korean tourist opened.

Police said unprecedented security at the Greymouth courthouse, on the South Island, was a precaution after white supremacists turned up to a previous hearing dealing with the murder of Jae Hyeon Kim.

The 25-year-old was believed to have been slain between September 29 and October 22, 2003 at remote Charleston, on the west coast of the South Island.

Three people were arrested after the cold case was re-opened earlier this year as a result of a tip-off from the public.

Details surrounding the arrested men remain cloaked in secrecy, and only one of those charged has been named, 28-year-old Nelson fisherman Shannon Brent Flewellen.

Two others have name suppression, including a 31-year-old former Westport man, but the nature and details of the charge relating to the third man is suppressed.

The depositions hearing, which is being held before two Justices of the Peace from Timaru and Ashburton, was stalled on Monday morning and was adjourned until the afternoon.

Crown prosecutor Chris Lange said he could not give the reason for the delay: "There is a reason, but that's as much as I can say".

Members of the Armed Offenders Squad stood sentry at the entrance to the courthouse, two guarded the back and another was positioned across the road at the entrance to the Greymouth Police Station car park.

A police dog handler was also wandering the surrounding streets.

Security guards and the police checked the identity of everyone entering the courthouse.