Immigration Minister Iain Lees-Galloway will review the case of a drug smuggler who was granted residency while serving jail time after "new information".

But National leader Simon Bridges has accused the minister of failing to do due diligence that has made New Zealand less safe and is urging the prime minister to sack him.

Karel Sroubek had been handed an unprecedented get-out-of-jail card in getting residency, instead of being deported after serving his prison sentence.

Lees-Galloway made the special decision, even though the 37-year-old Czech national came to New Zealand on a false passport and is now serving time in Auckland South prison for importing drugs with a street value of $375,000.

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Stuff Czech national Karel Sroubek, also known as Jan Antolik, was granted permanent residency, despite being in prison for importing MDMA.

Sroubek​ fled to New Zealand with a friend's passport in 2003. He claimed he was on the run from corrupt cops after witnessing a murder. Under the name Jan Antolik he built a new life as a businessman, a representative-level kickboxer, and a Hells Angels associate.

However, Newstalk ZB reported that Sroubek had already been back to the Czech Republic - which would mean his claim he'd be hunted down if he returned to his home country doesn't ring true.

On Wednesday, Lees-Galloway told Parliament that shortly before he arrived at Question Time he had become aware that "information may exist that appears on the face of it to directly contradict information that I used and relied upon to make that decision.

"I am now taking advice on my options and need to consider the veracity or the new information that has been made available to me."

The decision comes after Lees-Galloway's statements that he had re-read the case files and was sticking by his decision.

The minister tried to avoid reporters on the way into House on Wednesday by hiding behind a pillar for several minutes before telling them he was late to Question Time and would not talk to them till after.

But after Question Time, he told reporters it was a serious matter and he had sought urgent advice on what the course of action would be.

Lees-Galloway said he wanted to make clear that what has come to light was not additional information, but contradictory.

The information may exist and he needed to check it against the information he was given at the time he made the decision, he said.

When asked if the information related to Sroubek travelling back to the Czech Republic, he said he was not commenting on details until he was fully briefed.

"I wish this was not the case … obviously as a minister I rely on the information that I am provided. I have to make decisions based on that information and I need that to be sound and if it turns out not to be sound then I would need to consider what options are available to me."

When asked how the public could trust the immigration system and how he got incorrect information, he said it was something he would need to explore.

"That's why I need to take advice and look into this matter. If it turns out that I relied upon information that was incorrect, I take that very seriously."

Foreign Minister Winston Peters was asked on the way into the House about allegations that Sroubek had been back to the Czech Republic, raising questions about his reasons for needing to stay in New Zealand.

Earlier this week Prime Minister Jacinda Ardern told reporters to "read between the lines" as to why Sroubek had been allowed to stay in New Zealand despite his crimes.

Ardern would not give any detail on whether he was under threat in his homeland.

CARMEN BIRD Kickboxer Jan Antolik, whose real name is Karel Sroubek, is a Czech national who was jailed for importing MDMA into New Zealand. While in prison, Immigration Minister Iain Lees-Galloway granted him permanent residency.

When asked if there were humanitarian concerns or if Sroubek's life was in danger, she repeatedly referred reporters back to "past decisions" where "fair conclusions" could be drawn.

"Just glancing back at some of the past coverage of his entry into New Zealand, reading between the lines you can probably ascertain why the minister made the decision that he made," she said.

Lees-Galloway had told her about the careful consideration he gave the case and it was clearly a very difficult decision for him, she said. It was a decision that could have had "significant ramifications" and the minister did not take it lightly, she added.

Ardern said ministers of both political stripes will have come across "rare" cases such as this and there were about 40 a year.

Earlier, during Question Time, Ardern said the immigration minister had made his decision based on the information he was given and if there was any information to contradict that she expected the minster would go back to officials.

Bridges said Lees-Galloway had serious questions to answer after allowing "a dangerous, gang affiliated criminal" to remain in New Zealand, without fully considering the facts.

The minister should have asked more questions, done his own due-diligence and taken the decision to Cabinet, he said.

"Instead, he just took the case at face value, his decision was not in the public interest and it made New Zealanders less safe."

He said the minister needed to be capable of making important and dispassionate decisions that were in the best interests of New Zealanders.

"He's now trying to blame his officials. It was up to him to ask the hard questions. It's called 'Minister's discretion', not 'officials' discretion."

"The prime minister needs to front up to the fact that her Government has badly let New Zealanders down and she has no choice but to fire her Immigration Minister," Bridges said.