An 11-year-old boy from a nomadic family in Russia's north has stumbled upon a massive well-preserved woolly mammoth, in what scientists describe as the best such discovery since 1901.

Yevgeny Salinder, whose family lives near a polar station in the northern Taimyr Peninsula, discovered the frozen prehistoric animal when he was strolling along the banks of the Yenisei River in late August.

"He sensed an unpleasant odour and saw something sticking out of the ground -- it was the mammoth's heels," said Alexei Tikhonov, director of the Saint Petersburg-based Zoological Museum, who rushed to the tundra after the boy's family notified scientists of the historic find.

Tikhonov said it was the best preserved adult mammoth discovered in more than 100 years.

"So far we can say it is the mammoth of the century," Tikhonov said.

"An employee of the International Mammoth Committee and me went to the site," Tikhonov told AFP.

"Judging by its legs, it turned out to be quite a large mammoth, it was lying on its right side at the height of 5 metres (15 feet) above sea level. We had to start the excavation as soon as possible and there were just the two of us," he said.

Joined by employees of the nearby Sopkarga polar station, the scientists spent five days digging out the monster.

Tikhonov said the mammoth had died aged 15-16 around 30,000 years ago, adding that the tusk, skin, an eye and an ear were clearly visible.

"Its one-metre-long penis is also intact so we can conclude that this was a male," Tikhonov said, adding it also had one 1.5-metre-long tusk.

"Its skeleton is virtually intact and its heart in the rib cage may be intact, too."

The precious find weighing nearly one tonne was transported to the northern city of Dudinka and will later be brought to Saint Petersburg and Moscow where scientists can study it.

Tikhonov said that geneticists might be interested in trying to clone the animal, dubbed Zhenya after the nickname of the boy who discovered it, but he suggested that this would be difficult.

Global warming has thawed ground in northern Russia that is usually almost permanently frozen, leading to the discoveries of a number of mammoth remains.