By Charlotte Greenfield

WELLINGTON (Reuters) - A court in New Zealand has told the government to reconsider a decision to send back to China a man accused of murder, his lawyer said on Monday, spotlighting the hurdles the Asian giant faces in its quest to bring home alleged criminals.

The setback in China's first extradition request to New Zealand comes at a time when China is seeking to drum up international cooperation in a campaign to track down corruption suspects who have fled overseas.

In December, New Zealand agreed to extradite to Shanghai a South Korean-born resident, Kyung Yup Kim, but the Pacific country's High Court has decided the Chinese government's assurances of fair treatment for the man were not adequate.

"To get valid assurances you need to be able to monitor and enforce them," his lawyer, Tony Ellis, told Reuters, referring to fears over the risk of torture and an unfair trial Kim could face on his return.

A copy of the judgment was not immediately available, as the judge considered withholding some details.

A spokesman for Justice Minister Amy Adams said she could not comment because the full judgment had not been released.

In an affidavit in February, Adams told the court the Chinese government had assured her Kim would get a fair trial and would not face the death penalty.

It was not immediately clear how long the government might take to reconsider, or what fresh assurances it might have to seek from China. The death penalty is illegal in New Zealand.

Kim faced murder charges after the 2009 discovery in a Shanghai field of the body of a 20-year-old woman who had been strangled to death. He was put in prison after China sought his extradition in 2011, following his return to New Zealand.

Asked about the case at a daily news briefing in Beijing, Chinese foreign ministry spokesman Hong Lei said he did not know anything about it.

China has pushed for an extradition treaty with New Zealand since 2014. In April, on a visit to Beijing, Prime Minister John Key said an extradition treaty with China was "possible", so long as people did not face torture or the death penalty.

Up to 60 Chinese corruption suspects were in New Zealand, Key has said.

New Zealand police are investigating one of the suspects, an Auckland-based businessman. New Zealand has given China details of whether suspects were in New Zealand and their immigration status, a representative of the prime minister said last year.

(Reporting by Charlotte Greenfield; Additional reporting by Ben Blanchard in Beijing; Editing by Clarence Fernandez)