Reports that hundreds of parking machines could be infected with a credit card number harvesting virus are unfounded, the head of Wilson Parking says.

Chief executive Steve Evans said no virus could affect pay-and-display machines, which did not contain a computer like some in Hamilton did.

It was reported today that a compromised machine in Wilson Parking's Alexandra St car park in Hamilton was displaying an error message this week.

The message warned that the machine was infected with the Conficker virus – the same virus that disabled Waikato District Health Board's 3000 computers in 2009.

"I would definitely not put my credit card in this machine or any Wilson Parking machine until I felt confident that the system had been fixed," Aura Information Security managing director Andy Prow told the newspaper.

However, Evans said no machines anywhere in the country had been hit by a virus.

The warning seen on the Hamilton machine came from its anti-virus software, which had detected a virus threat.

The threat had not breached the anti-virus software, but even if it had there was no chance it could spread or affect machines in Christchurch, he said.

"We don't have any of that sort of equipment in Christchurch. None of the pay-and-display machines use that kind of technology," Evans said.

"The message that popped up is just to let us know a threat had been detected."

Wilson Parking had just under 40 car parks in central Christchurch, Riccarton and around Christchurch Hospital.

Christchurch's machines used a General Packet Radio Service (GPRS) wireless network to process credit card payments, and each machine was independent from the others, Evans said.

"It's done in real time and in such a way that it's just impossible to harvest it. None of the modern systems is at risk," he said.