The Biosecurity Minister is not budging on the stink bug issue.

Damien O'Connor says it is up to those importing and transporting vehicles to New Zealand to do it without bringing potentially devastating biosecurity threats in too.

The pests have been discovered on board four ships from Japan this week, and all have been told to turn around.

The Minister Damien O'Connor says there are clear requirements for imports here, and those must be met.

"We have more people going off shore to warn those who might be exporting into our country that we are not going to tolerate this. To assist them with the ways of treating the cargo shipment before they get on the boat."

He says it's a bug that could cause billions of dollars in damage to the economy, and he's not letting it anywhere near us.

"We cannot afford to let it in and we will shut down the pathways wherever we find them."