The Immigration Minister's decision to give a convicted Czech drug smuggler residency was "always clearly wrong", National Party leader Simon Bridges says.
Iain Lees-Galloway has been forced to review his decision after information he had not previously been briefed on was reported by the media.
Jan Antolik, also known as Karel Sroubek, was jailed two years ago, for more than five years, for importing about five kilos of MDMA.
He was refused parole in September, with the board saying it considered he presented a complex and more comprehensive risk of re-offending than his criminal conviction history in this country would betray.
Reading between the lines of what both Prime Minister Jacinda Ardern and Mr Lees-Galloway have been saying, it is clear Sroubek wanted to stay in New Zealand as he feared for his safety if he returned home.
But Newstalk ZB reported yesterday that he had already been back to the Czech Republic, meaning those fears did not hold much water.
Just before he got to Question Time yesterday, Mr Lees-Galloway was advised there could be more information that could contradict that which he used to make his decision.
He told reporters it was a "very serious matter".
"It would be inappropriate for me to make any comment until I have determined the veracity [of the information] and the appropriate course of action."
Mr Lees-Galloway refused to say whether the contradictory information was that reported by Newstalk ZB, but on his way into Question Time yesterday he was seen urgently speaking to the network's political editor.
National Party leader Simon Bridges told Morning Report Mr Lees-Galloway should resign because the decision "was so serious and was always, it seems to me, clearly wrong".
"He just hasn't done his job, he hasn't exercised the judgement, the acumen that it seems to me any competent minister would in this case."
Mr Bridges acknowledged there were questions about why Karel Sroubek wasn't deported under the previous government.
But he said Immigration New Zealand had confirmed the case never went before the immigration minister in the National government.
"I'm not expecting, unreasonably, ministers to be detectives but I think what New Zealanders would expect is when they do get the decisions before them, as Iain Lees-Galloway does, when it is their discretion, that they do it with good judgement and competence and they keep New Zealanders safe. And Iain Lees-Galloway hasn't."
Mr Lees-Galloway was asked whether the change in circumstance was embarrassing.
"I certainly wish that this wasn't the case, but first of all I have to check the veracity of this additional information.
"But obviously as a minister I rely on the information that I'm provided.
"I have to make decisions based on that information, I need that information to be sound and if it turns out that information that I had was not sound then I need to consider what options are available to me."
Deputy Prime Minister Winston Peters said there were out clauses which meant Mr Lees-Galloway's decision could be reversed.