Air New Zealand is offering customers carbon credits to offset emissions from their travel and is investing in forest planting to reduce its own pollution. Customers will be able to buy credits, initially sourced from a New Zealand wind farm owned by TrustPower, chief executive Rob Fyfe said in a statement today. The company will also fund a three-year tree planting program to help offset emissions from staff travel. Air New Zealand promotes the country's clean environmental image to fill international services, which account for about two-thirds of its revenue. It is buying fuel-efficient planes to cut emissions and fuel costs and will this year test biofuels in a joint study with Boeing and Rolls-Royce. Customers ''will now be able to make a conscious choice about whether or not to take positive steps towards helping our environment,'' Mr Fyfe said in the statement. Offsetting emissions on a flight from Auckland to Wellington will cost NZ$4.50 ($A4.00), rising to NZ$13.70 for a Christchurch to Sydney service and NZ$88.10 on an Auckland to Los Angeles trip, the airline said. Customers can also donate to an environmental trust, which the airline is underwriting with an initial NZ$450,000 donation and will support with ongoing contributions. The fund's first project is a native tree restoration on 40 hectares on Mangarara Station in Hawkes Bay. Bloomberg