Sydney hospital cleaner charged with being North Korean agent

Intriguing details are emerging about the Sydney man accused of brokering the sale of weapons of mass destruction for North Korea.

Chan Han Choi, a 59-year-old man from South Korea, has lived in Australia for three decades, raising questions about how he fell under the influence of the rogue state.

Choi worked as a hospital cleaner by day, a suspected North Korean agent by night.

According to Australian Federal Police assistant commissioner Neil Gaughan, Choi was "brokering the sale of missile componentry and technical expertise from North Korea to other international entities". 

Choi was arrested at his home in northwest Sydney on Sunday (local time). Police also seized computers, disk drives and documents.

He is facing six charges, including the first ever laid under Australia's Weapons of Mass Destruction Act.

"I know these charges sound alarming, but let me be clear," commissioner Gaughan said. "We are not suggesting there are any weapons of missile componentry that ever came to Australian soil." 

Prime Minister Malcolm Turnbull called Choi's arrest "very, very important".

"The charges that are being laid are of the gravest nature," he said.

Choi lived in South Korea for 29 years. He moved to Australia in 1987 and later became an Australian citizen.

Police allege he started offending in 2008, brokering sales of missiles and componentry, technical expertise, even coal, gemstones and oil.

The Australian Federal Police have also confirmed at least half a million dollars was wired to Pyongyang, and there were deals in place for tens of millions more. 

North Korea expert Dr Leonid Petrov says this shows the rogue state is becoming desperate.

"The North Korean government is very hungry for cash at the moment and there is a market for weapons of mass destruction," he says.

Choi has been refused bail and will appear in court later this week.