The Czech drug smuggler at the centre of an immigration storm did travel to Europe in 2009, court documents show.

That was despite implications that Karel Sroubek's safety was at risk if he returned to the Czech Republic.

Immigration Minister Iain Lees-Galloway has now ordered Immigration New Zealand (INZ) to investigate Sroubek's residency application to see if he received the correct information when making his decision.

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

The investigation would be done by INZ's compliance team and is understood would examine new allegations that Sroubek had already been back to the Czech Republic, and his ex-wife is no longer supported in his application.

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However, it was revealed on Thursday that 2009 court documents show a "variation of bail" application was granted by the High Court in Auckland under Sroubek's false name (Jan Antolik), to allow him to travel to the Czech Republic for business.

WARWICK SMITH/STUFF Immigration Minister Iain Lees-Galloway reviewd the case of a drug smuggler who was granted residency after "new information".

He returned to Europe, but it is uncertain whether he travelled to the Czech Republic.

National's immigration spokesman Michael Woodhouse said the existence of the court documents showed the minister had not done his homework.

"It was very clear on the public record what had been speculated - that despite claims of fear of being sent back to Czech Republic, he was voluntarily going back and living in plain sight. It speaks to the shabby way this decision has been made."

National's Justice spokesman Mark Mitchell said it took his party about one day to uncover the information about Sroubek from "brave" people involved in the court cases as well as retired immigration officers and police detectives.

They rejected Sroubek's story and saw it for what it was - a complete fabrication, he said.

He was confident more information would likely come to light.

Three weeks for an investigation was "ridiculous " and the minister should be reporting back by Friday, he said.

He would be "shocked" if the immigration probe did find the residency decision should be reversed.

Lees-Galloway rejected speculation that public documents were the information he had not received.

He said the debacle highlighted it would be a worthwhile exercise to reflect on the decision making process, to see if improvements could be made.

"I believe this case demonstrates there is an opportunity to reflect on process that have been in place for quite some time, and the nature of the information provided to ministers and how those decisions are reached."

The document disclosure comes after Lees-Galloway revealed on Wednesday that "new information" existed that "directly contradicted" what he used to make his decision - however, he will not comment on details.

The drug smuggler, who was granted residency while serving jail time, was handed the unprecedented get-out-of-jail card, instead of being deported after serving his prison sentence.

Lees-Galloway made the special residency decision, even though the 37-year-old Czech national came to New Zealand on a false passport.

Prior to the legal documents coming to light, the minister announced he had given Immigration New Zealand three weeks to investigate if evidence existed that contradicted the information he had.

"As a decision maker I can not rely on innuendo, hearsay or speculation, but these allegations certainly are concerning for me. I therefore have instructed Immigration New Zealand to investigate these allegations to obtain the veracity of that information."

When asked if there was a possibility of criminality against Sroubek, he said for legal reasons he would not go into any of those matters.

Earlier this week, Lees-Galloway was firmly standing by his decision and was backed by Prime Minister Jacinda Ardern.