Lonesome George, the last remaining Galápagos giant tortoise, may soon be a father after years of efforts by scientists trying to get him to mate.

Ecuadorian officials are keeping their fingers crossed for Lonesome George, aged between 90 and 100 and described by the Guinness book of world records as the "rarest living creature", after one of the two female tortoises kept with him laid five eggs.

George, said to be at his sexual peak, is the only known living Geochelone abigdoni tortoise. His companions are of a similar but different species. Scientists at the Galápagos national park have been trying for years to get George to avail himself of his female companions to ensure that his line does not peter out.

Lonesome George, weighing 90kg (14st 2lb) was a native of Pinta, an isolated northern island of the Galápagos. By the late 1960s, it was noted that the tortoise population on the rarely visited island had dwindled close to extinction. George, discovered in 1972, was immediately brought into captivity at the Charles Darwin research station on the island of Santa Cruz .

Scientists have been trying to get George to mate since 1993, when they introduced two female tortoises of a different subspecies from the neighbouring island of Isabela into his pen, but he has been in no hurry to procreate.

George astounded 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.

The national park has said that the latest eggs, described as being in perfect condition, are being cared for in an incubation centre. It will be November before scientists know whether they are viable .

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

Tortoises on the Galápagos have been hunted for their meat by sailors and fishermen to the point of extinction. Charles Darwin, when he arrived in the Galápagos in 1835, described how he and the crew of the Beagle lived entirely on tortoise meat. Also, the habitat of the tortoises has been eaten away by goats introduced from the mainland.