Czech smuggler previously had residency - under a false identity

Immigration Minister Iain Lees-Galloway has released a letter outlining the conditions a drug smuggler from the Czech Republic must abide to remain in New Zealand.

Jan Antolik, whose real name is Karel Sroubek, was jailed for five years for importing nearly 5kg of MDMA, commonly known as Ecstasy, with a street value of $375,000.

Mr Lees-Galloway said the decision to grant residency was made after careful consideration of all the information available at the time and that the man's stay in the country was subject to significant conditions.

He said he can't discuss the reasons he granted him residency for privacy and legal reasons.

But he has released a letter he wrote to Mr Sroubek, outlining the conditions he must abide by in order to stay in New Zealand.

They include not reoffending, not using a fraudulent identity or misleading a government agency within the next five years.

The letter also noted Mr Sroubek had been given a residency visa previously, but that was under a false identity.

Mr Lees-Galloway says he made the decision in light of the "full view of information" presented to him, and was not made lightly.

In the letter, Mr Lees-Galloway said this "was a very serious matter" and urged Mr Sroubek to make the most of his "final chance" to stay in New Zealand.

"Please note that cancelling your liability for deportation on this occasion does not prevent you from being liable on other grounds.

"I trust you will use this opportunity to make a positive contribution to New Zealand."

Prime Minister Jacinda Ardern said it was not any easy decision for the minister, but it was made after considering all of the information at hand.

Read the full letter released by the Immigration Minister here:

National Party immigration spokesperson Michael Woodhouse said questions need to be answered because he didn't believe the threshold for residency had been reached.

Immigration lawyer Marcus Beveridge from Queen City Law agreed.

He told Morning Report the discretion used by the minister under the Immigration Act raised significant public interest questions and that it was in the minister's interest to front up over the decision.

"We haven't seen a decision of this nature before where, on the face of it, without knowing all the facts, it almost appears as though crime pays," Mr Beveridge said.

"The ministerial discretionary powers are an important part of the immigration process, but not all people fit into boxes. So, you apply to Immigration, if that's declined you appeal to the Immigration Protection Tribunal.

"Then you'll got a crack at the minister because you're begging for mercy effectively and then for those sophisticated punters there are judicial reviews in the courts if you can afford it.

"But normally for justice or equity to be exercised the applicant would have clean hands and in this case, from what we have been able to discern so far, from media reports, nothing could be further from the truth.

"And you have to wonder what message this will be sending internationally."

Mr Antolik was denied parole this year when a report that stated the parole board considered the man presented a complex and more comprehensive risk of reoffending than his criminal convictions history this country would portray.

Mr Beveridge said the public deserved to know the facts surrounding the case.

"Really in this case, in terms of whether or not it should be in the public arena, I think it's a no-brainer, the guy has probably had over $1 million worth of taxpayers' money spend on him if you take into account his multiple criminal charges, plus the issues associated with prosecuting him, and I assume he's been on legal aid, and then $100,000 per year in jail for five years," he said.

"It's very much in the public arena, so the minister would be wise to front-foot this and explain whatever issues have influenced him to find in this chap's favour, and reward him with a resident's visa while he was in jail."