Immigration Minister Iain Lees-Galloway is urgently reviewing his decision to grant residency to a Czech drug smuggler after receiving "new information".

Jan Antolik, also known as Karel Sroubek, was given New Zealand residency despite currently serving time in prison for importing about 5kg of MDMA, commonly known as ecstasy.

However Mr Lees-Galloway told Parliament on Wednesday he had become aware of potentially new details which appeared to directly contradict information he'd relied upon to make his decision.

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

The minister has previously refused to discuss the reasoning behind his decision, but past news reports would suggest there could be a risk to Sroubek's life if he returned to the Czech Republic.

In Parliament today National said he had been back to the Czech Republic since the early 2000s.

National leader Simon Bridges told reporters if the "remarkable" story was true, it appeared the Minister had been "duped".

"If you say this is some form of humanitarian basis because he can't go back because maybe he's scared, well, he did just that - he went back, he wasn't scared.

"They know they've got no good reason. They were duped. They were naive."

Prime Minister Jacinda Ardern has defended Mr Lees-Galloway, saying the minister had to rely on the information provided to him by officials at the time.

Mr Lees-Galloway told reporters he would be making no further comment until after he'd received further advice and checked the veracity of the new information.

"If it turns out that I relied upon information that was incorrect, I take that very seriously and that is why I am taking advice on what the appropriate course of action would be."