Lonesome George, the last remaining giant tortoise of his kind, may soon be a father to the delight of conservationists.

Unhatched eggs have been found in his "bachelor" pen in the Galapagos Islands, his keepers said.

For decades, the last known Pinta island tortoise had shown little interest in reproducing. But at age 90, George is said to be in his sexual prime.

Galapagos tortoises were among the species Charles Darwin observed to formulate his theory of evolution in the 19th century.

Scientist have been trying to get George to mate since 1993, when they introduced two female tortoises of a different subspecies into his pen.

The Galapagos National Park said the five eggs found on Monday were "in perfect condition" and have been placed in an incubator.

"Now we have to wait for the incubation period of 120 days to find out whether they are fertile," it said in a statement.

The 90-kg George stunned conservationists last year by mating for the first time in the 36 years he has been in captivity. But the eggs laid by one of his female companions turned out to be infertile.

Tortoises were hunted for their meat by sailors and fishermen to the point of extinction, while their habitat has been eaten away by goats introduced from the mainland.

Some 20,000 giant tortoises still live on the Galapagos.