Britain has been warned by the United Nations that it is at risk of losing two of its five listings for natural World Heritage sites unless it urgently provides funding to eradicate rodents threatening critically endangered bird species found only on two remote islands.

Rats and mice introduced on to the British-administered Henderson Island - part of the Pitcairn Islands - and Gough Island in the South Atlantic are destroying unique bird populations, including breeds of petrel and albatross, by eating vast numbers of eggs.

Unesco, the United Nations heritage body, this week warned that the status of the islands as natural World Heritage sites was in danger of being removed unless work was done to stop the birds being driven to extinction. The Royal Society for the Protection of Birds described the intervention as "extremely embarrassing" for the Government and called for £700,000 ($1.52 million) to be provided towards the £1.7 million cost of clearing Henderson Island of its 30,000-strong population of the Pacific rat introduced by Polynesians in the 14th century.

The subtropical island, and Gough Island, is one of 14 British Overseas Territories and the direct responsibility of London. It is home to five species found nowhere else on earth, including the Henderson petrel which once numbered five million pairs but now stands at just 40,000 pairs. The two islands are uninhabited and among the most inaccessible places in the world.

Ornithologists warn the petrel could be extinct within a few years unless urgent action is taken to kill the rats, which eat 25,000 chicks a year - equivalent to 95 per cent of the eggs laid by the birds. The Tristan albatross, one of three species unique to Gough Island, is suffering a similar rate of decline due to supersized domestic mice which have grown fat on the easy prey of newly hatched chicks.

Society spokesman Grahame Madge said: "For the British Government to be told that it is currently failing the designation of these islands as World Heritage sites is extremely embarrassing."

A Foreign Office spokesman said nearly £440,000 had been provided to protect bio-diversity in Overseas Territories and it would welcome an application from the society for further funds.

- The Independent