IT'S a case of mistaken identity. A "snake" found on a Air New Zealand flight this week is now thought to be a legless lizard.

The reptile was found near the back of a plane travelling from Brisbane to Auckland on Tuesday night and was caught by the flight's service director. About 50 centimetres long, it was believed to be a non-venomous green tree snake.

Agriculture and Forestry Ministry spokesman Brett Sangster said yesterday that a New Zealand herpetologist identified the lizard from a photograph by its distinctive earholes.

The reptile, now dead, had been sent to the herpetologist and it was hoped its identity could be confirmed within the next two days, Mr Sangster said. It was thought the lizard belonged to a group of Australasian lizards that appear legless but retain remnants of legs.

Ministry and Customs staff were trying to find out how the reptile got on the plane. It might have stowed away in hand luggage or could have been taken on deliberately.