Air New Zealand's airfreight business is being investigated by the country's Commerce Commission over allegations of price-fixing.

Commission spokeswoman Kate Camp said the investigation concerned issues raised in the AUD200 million (US$154.48 million) class action filed by Australian law firm, Maurice Blackburn Cashman, earlier this month against Air New Zealand and six other airlines. The class action is believed to have been filed after the commission initiated its probe.

The airlines are accused of forming a price-fixing cartel to collude over fuel, security and war-risk surcharges against Australian freight users since 2000. The carrier has denied any wrongdoing.

Media reports speculate that the commission's investigation may be related to a raid by the Commerce Commission on Air New Zealand's head office in September last year, which resulted in a number of documents being confiscated for closer examination.

This is similar to what happened in February last year when EU and US investigators raided the offices of more than a dozen airlines worldwide over allegations of price-fixing in the airfreight industry.

Air New Zealand said then it was fully co-operating with the commission over an investigation that related to a "small part of the company's business since before 2001", adding that it did not think the probe would have financial implications for the carrier.