A Malaysian-based airline has been fined $9000 for allowing an unauthorised passenger to board a flight to New Zealand.

AirAsia X pleaded guilty to failing to comply with the airline's obligations under the Immigration Act after it defied Immigration New Zealand's (INZ) requests not to board the passenger.

Stephanie Greathead, INZ's national manager of the border, said the actions of AirAsia X were a clear breach of New Zealand's border security measures and completely unacceptable.

"The airline has clearly tried to override the APP system and ignored any do not board directives. This is completely unacceptable and is in clear breach of our border security measures and immigration policies," Greathead said.

Under the law, airlines must submit data on people intending to board an aircraft travelling to New Zealand. This occurs at the time of check-in so that any clearance requirements can be obtained on passengers before they board the airline.

Passenger clearance is obtained through a system known as the Advance Passenger Processing System (APP). Once the data is entered by the airline handling agent, it is sent to the APP system which is linked to INZ's database. A message is automatically generated advising whether the passenger is permitted to board or not, whether contact with INZ is required, or whether there are any conditions of boarding.

Greathead said that at the time of check-in, AirAsia X's handling agent submitted the traveller's name into the APP system and received a 'do not board' directive.

"The handling agent then made several other attempts to check-in the traveller and then submitted an incomplete name into the APP system, before receiving a directive to 'Board with Outward Ticket'.

"AirAsia X then allowed the passenger to board the Kuala Lumpar flight and travel to New Zealand," Greathead said.

The Malaysian citizen involved in the incident had attempted to board a flight bound for New Zealand from Kuala Lumpur in February last year. That passenger was refused entry to New Zealand on arrival and sent back to Malaysia.

AirAsia said this afternoon it was committed to the laws and regulation of the countries in which it operated.

"Upon notification of this incident, we conducted a thorough review and took appropriate corrective action," said a spokesman.

As part of ongoing compliance measures, the airline would continue to review internal procedures and ground handler training to prevent more cases, he said.