The SPCA is urgently appealing for help from the public after two kittens were thrown from a moving car on an Auckland motorway.

A witness saw the two kittens being hurled from the car early yesterday afternoon, near the Greenhithe Bridge heading toward Albany.

One kitten survived the incident with minor injuries, but her sibling died.

She's being treated at the SPCA's Animal Hospital.

The organisation said it's a despicable act that inflicted serious pain and suffering on two innocent cats.

It said it's important that those responsible for the cruelty are held accountable.