The Crown has spent more than $1 million on a seven-year battle to extradite a Korean-born New Zealander accused of murdering a woman in China.

Kyung Yup Kim has been fighting attempts to send him back to China since his arrest in 2011, and spent five of those years in custody.

No New Zealander has ever been extradited to China.

Mr Kim's lawyer, Tony Ellis, says the Crown wanted to set a precedent so it was easier for China to have so called "economic criminals" sent back to stand trial.

Since May 2011, when China first requested that New Zealand send Mr Kim back, there have been six hearings relating to the legality of his detention, two judicial reviews and one appeal to the extradition order.

Figures given to RNZ show Crown Law spent $661,535 on the extradition hearing and $90,019 representing the Department of Corrections, defending the legality of Mr Kim's detention.

The Ministry of Justice has spent $387,521 on judicial reviews, bail hearings and providing advice to the justice minister.

Another $95,747 has been spent on legal aid for Mr Kim's defence.

Dr Ellis is representing Mr Kim and fighting the extradition on grounds that include concerns he would not get a fair trial.

Mr Kim was receiving legal aid but the battle was one-sided, Dr Ellis said.

"I thought how modest my fees were - $96,000 - and they've spent $1.2 million, they've spent 12 times as much as we have," he says.

Canterbury University law professor Neil Boister says the amount spent in Mr Kim's case was not exorbitant by extradition standards, but extradition was a notoriously expensive process, because it involved two countries and took a lot of time.

Dr Ellis suspected the Chinese were pursuing Mr Kim to fulfill a broader agenda, specifically the 100 fugitives China says it wants to answer charges of corruption and other alleged crimes, with suggestions up to 20 of them may be living in New Zealand.

"They published a wanted list of 100 economic criminals and most of them on that list, we're talking about hundreds of millions of dollars," Dr Ellis says.

"They want to set a precedent that it's all right to extradite to China and Mr Kim [is] probably a useful precedent for them."

Professor Boister says China has pursued economic criminals in Canada and Australia, in a bid to send a clear message that those who engage in corruption in China can't seek refuge overseas.

If Mr Kim lost his appeals, it would make it easier to extradite others, but not for any legal reason, he says.

"It will simply familiarise the two states involved that are party to this extraditon process, with each other's procedures. They will begin to understand how the other works."

Justice minister Andrew Little would not comment on Mr Kim's case, which is currently subject to an appeal in the Court of Appeal.

However he was unlikely to overturn the decison of his predecessor Amy Adams, who had agreed to extradite Mr Kim, he says.

"It would be very unusual for a new minister coming in to just unilaterally overturn an extradition decision by a previous minister, there's got to be public confidence in the process and it should not be politicised."

Dr Ellis says his client could appeal to the United Nations once all avenues in New Zealand had been explored, meaning any final decision could still be several years away.