Tonga says it's called in expert consultants to review the profitability of the Nuku'alofa-Apia-Los Angeles route, serviced by Air New Zealand.

The move comes in the wake of an ultimatum put to the Tongan and Samoan governments last week by Air New Zealand.

The airline wants the two governments to subsidise the North American route, to make it more profitable and says if they don't, Air New Zealand may pull out of the Los Angeles connection.

The Samoan Deputy Prime Minister, Misa Telefoni, accused Air New Zealand of holding it to ransom on Oct. 27.