Lonesome George the tortoise has died, leaving the world with one less subspecies.

The only remaining Pinta Island giant tortoise, a celebrated symbol of conservation efforts in the Galapagos Islands, died on Sunday with no known offspring, the Galapagos National Park in Ecuador said.

Lonesome George's longtime caretaker, Fausto Llerena, found the giant tortoise stretched out in the "direction of his watering hole" on Santa Cruz Island, the park said.

The cause of George's death remains unclear. An autopsy is planned and Lonesome George, estimated to be more than 100 years old, is being kept in a cold chamber to prevent decomposition before the procedure.

Lonesome George was discovered on Pinta Island in 1972 at a time when giant tortoises of his type, Geochelone nigra abingdoni, were believed to be extinct.

Since then, the animal had been part of the park's tortoise programme, but many efforts to breed with Lonesome George failed.

"The plight of Lonesome George provided a catalyst for an extraordinary effort by the government of Ecuador to not only restoretortoise populations throughout the archipelago, but to also improve the status of other endangered and threatened species," the park said.

A park spokesman said an international workshop on management strategies for restoring tortoise populations over the next decade would be convened next month to honour Lonesome George.

The Galapagos Islands, about 1000km off Ecuador's coast, are considered a haven for tortoises.

There are about 20000 giant tortoises left there, according to the park's website. They are believed to live up to 200 years.

The Galapagos gained fame when Charles Darwin conducted landmark research there in 1835.