Minister of Immigration Kris Faafoi says he has been assured the 10 men facing deportation to China have been afforded their rights.
Two of the 10 men - who officials say were working illegally at construction sites in Auckland - are due to be deported at 11pm tonight - and some others in the next week, according to their lawyer.
Green MP Ricardo Menendez-March, who was among a delegation to visit the men on Thursday, wants the deportations paused to allow an investigation into claims of migrant exploitation and human trafficking.
But Faafoi said he had been assured the proper processes were followed and Immigration had not found any evidence of trafficking.
In a statement, Faafoi said: "We have been assured that the appropriate processes have been followed and Immigration NZ has not found any evidence of trafficking. Agencies are satisfied further investigations around employment and immigration breaches can be carried out without the need for the men to remain in New Zealand".
Ministers did not get involved in enforcement and it was an operational matter, he said.
However, Matt Robson, the lawyer for Chinese workers, said they could not be deported until a full investigation was carried out.
Robson visited the men at Mt Eden prison with Menendez-March and representatives from Unite Union on Thursday. Nine are believed to be held at the prison and another in police custody.
Speaking outside the prison, Robson, said the men were victims of human trafficking after paying between $10,000 and $30,000 to a third party who arranged travel and work.
The men had no contract and some were paid $8 to $10 per hour, and exploitation was obvious.
"If I was any of the employers involved, I'll be laughing now that immigration New Zealand is doing my job to get rid of the witnesses," Robson said.
Some of the men were granted a visitor visa in just two days and Robson questioned why visas were seemingly granted at lightning speed.
Third parties in China and New Zealand were involved and there needed to be an investigation, Robson said.
"The government policy migrant exploitation policy is very clear. We're going after the perpetrators of trafficking and exploitation, not the victims. The Cabinet Manual says that if you're a minister, you have to carry out government policy. You have to act in the public interest, and you can't run away from the law and policy. Our Minister immigration at the moment is missing in action."
Robson said they were allowed into Mt Eden for two hours on Sunday and only one hour on Thursday with an interpreter from the Unite Union. It was far too little time to get adequate information from the nine men, Robson said.
He was calling for the the men's release, and said they should be given visas to stay for an investigation to take place.
Menendez-March was concerned about the men's welfare after meeting them and said the two men due to leave tonight did not know that.
"The clear indication by the majority is that not only are they feeling incredibly stressed, that inside corrections, they haven't had access to interpretation, which is concerning in regarding to their wellbeing," Menendez-March said.
Given the men had signalled they had been exploited, a thorough investigation is needed, he said.
Deporting them was against Immigration New Zealand's rule to encourage people facing exploitation to speak up and a signal needed to be sent, he said.
Unite Union advocate Mike Treen said he was disappointed by claims the men weren't given proper representation. His union was willing to take the men into its care if they could be released.
"If they are released, we can find accommodations for them, we can find work for them if they are allowed to work and we can assist the government and the agencies to expose the network that allows this human trafficking to occur," he said.
Immigration New Zealand deputy head Stephen Vaughan said his department obtained Warrants of Commitment from a District Court judge for all 10 men.
"INZ can provide an assurance that all of the individuals have been advised of their rights to legal representation while in INZ's care, both when they were detained and again when they were transferred into police custody. The workers all had access to a duty lawyer and interpreter at the Warrant of Commitment hearing," Vaughan said.
"No breaches of employment standards have been identified so far but the investigation is in its early stages and if any breaches are identified the Labour Inspectorate will support the INZ investigation. INZ continues to look at any possible breaches of the Immigration Act, while the Labour Inspectorate will look at any possible breaches of employment standards."
A corrections spokesperson said the men were allowed access to calls and interpreters.
"The men are allowed to access as many calls that are able to be facilitated by staff. Corrections staff have been working with the men to facilitate phone calls but have not been able to connect with all of the numbers provided.
"There are four staff based in the accommodation where the men are located who speak fluent Mandarin, and several others on site. Since their arrival, these staff have been working closely with the men to translate and explain their management in prison."
It said reports that Corrections ignored requests for a legal representative to visit the men were incorrect as it had facilitated requests for visits on Sunday and Thursday.