Former spy minster Andrew Little says a police trip to China looks like a "classic effort" by the Chinese government to "curry favour" with New Zealand authorities.
A group of 33 police staff visited China in October in what the police say was a "private, self-funded trip" to increase cultural competency.
On Monday the agency that acts as a police watchdog, the Independent Police Conduct Authority, confirmed it had received a formal complaint about the trip.
Political scientist Anne-Marie Brady said the trip has all the hallmarks of a political interference operation.
Former Minister for the NZ Security Intelligence Service (NZSIS) and Government Communications Security Bureau (GCSB) Andrew Little said it looked like a bid to build influence.
"This looks like a classic effort on the part of the Chinese government or Chinese authorities to curry favour and build a loyalty amongst serving police officers in New Zealand and that ought to be a worry," he told RNZ.
"When you have a group of people, in this case serving police officers, travelling to China admittedly at their own expense but apparently being hosted at the expense of others once they're in the country, then that looks like a classic influence building programme or influence building effort, and for that reason, it ought to attract some attention."
Police Assistant Commissioner Tāmaki Makaurau Sam Hoyle earlier told RNZ police took part in "a private trip" to China "encouraging cultural competency" in October.
All participants were on annual leave at the time and paid for travel costs and expenses themselves, he said.
Those who attended reported an "incredibly positive and beneficial experience".
The trip was organised by Auckland police ethnic responsiveness manager Jessica Phuang, "a highly regarded leader in Tāmaki Makaurau", and facilitated by a professional tour company.
All "appropriate notifications and processes were carried out" prior to departure, and "no provincial governments hosted the group", Hoyle said.
All police- issued devices were left behind in New Zealand, Hoyle told Morning Report.
Little said New Zealand's intelligence agencies spent a large chunk of their time dealing with foreign interference, and China had a "very sophisticated programme of work" to influence others.
"There's always these efforts to build relationships and ultimately influence. It could be councillors or local government officials, it could be with politicians or any rank or type, backbenchers as well as ministers.
"Anybody with a level of influence, knowledge and understanding about New Zealand and New Zealand decision making of politics and institutions, then there are those from other countries who want to know about it and have an influence over it, and China has a very sophisticated programme of work to achieve just that."
Little said it would be important for the police hierarchy to take a closer look at the officers' disclosures and the extent of the hospitality they enjoyed at the expense of provincial or Beijing governments during October's trip.
"When you're got serving police officers on a trip like this, where they apparently were hosted by certain provincial governments and possibly the central government of China and the Chinese Communist Party, that's a matter that ought to be disclosed or should have been disclosed before the trip took place.
"One of the things we pride ourselves on the New Zealand Police force is it is almost entirely free of corruption. There's the isolated example here and there, but we do that because things are transparent and we have a police hierarchy that looks out for these things.
"We don't want our police officers, at whatever level and rank, to hold a loyalty to institutions or causes other than the service of the New Zealand Police. So this stuff does need to be highly transparent and police hierarchy needs to look at it."
Little said accommodation and meals the officers did not pay for themselves should be considered gifts and declared.
"If you're getting a benefit that you're not paying for yourself, and particularly if it's at the expense of a foreign, provincial or central government, that definitely has to be declared.
"And if you're a serving police officer then that ought to be declared before you go, but there should be a full accounting of it once you're back."
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