Police say six years on from a Christchurch woman's disappearance, hope of finding her alive has almost vanished.

Police are offering a $30,000 reward for fresh information about the disappearance of Yoon Sook Chun.

Detective Sergeant Ross Tarawhiti says she went missing from the Aidanfield suburb of Christchurch in 2009, after emailing her family saying she was going to Auckland for a break. No-one's seen or heard from her since.

"Her bank accounts haven't been touched so it's highly unlikely she is still alive at this stage. Obviously if she is alive she would have had to have help to live and work in New Zealand."

She held both a New Zealand and South Korean passport, but neither have been used to travel.

Anyone with information is asked to contact Christchurch Police.