Wellington  - The first nest of eggs laid by tuatara reptiles - living fossils who are descendants of the dinosaurs - has been found on the New Zealand mainland in more than 200 years, the Karori Wildlife Sanctuary reported on Saturday.

Staff found four ping-pong-ball-sized leathery white eggs while doing routine maintenance work near the 8.6 kilometre predator-proof fence around the 225-hectare sanctuary in suburban Wellington, manager Raewyn Empson said.

She said they were immediately covered up to avoid disturbing the nest which could contain up to 10 eggs that should hatch between now and March.

Tuatara (Sphenodon punctatus), which are unique to New Zealand, are the only survivors of the dinosaur-like reptile species Rhynchocephalia, which became extinct about 60 million years ago and scientists refer to them as "living fossils."

Rats destroyed the population on the New Zealand mainland more than 200 years ago, but small numbers remained on offshore islands.

Some were moved to the Karori sanctuary in 2005 to re-establish them on the mainland in a predator-proof environment so that more New Zealanders could see them.