Endangered kakapo are being moved off Fiordland's Anchor Island as a precaution after a 700kg load of rat poison fell from a helicopter yesterday.

The load of brodifacoum cereal pellets landed in the large freshwater lake on the island, a safe haven for kakapo, The Otago Daily Times reported.

Eight hectares of land surrounding the lake had been searched but no pellets found.

"Two kakapo in the vicinity of the lake have been removed to another island as a precaution. It is highly likely all the poisoned baits landed in the lake," Conservation Minister Kate Wilkinson said.

Brodifacoum is a highly lethal poison which breaks down in water.

The Department of Conservation will monitor the lake over the coming weeks.