It was uncovered in a volcanic cave in Antofagasta, which is in the northwestern province of Catamarca.

This is high in the Andes - 3,600 metres (11,800 feet) above sea level - and the very cold and dry air at this altitude preserved the baby by a process of freeze-drying.

"The baby seems to be have been no more than four months old. It died of natural causes and was buried in a leather wrapping," Carlos Aschero, head of the Institute of Archaeology of Tucumán University, said.

The discovery was something of a surprise for the researchers who did not know what to expect when they X-rayed a bundle of leather and straw.

"We only realised what it was when X-rays were done and showed the shape of the baby. We had this bundle, but we did not really know what it contained," Aschero said.

"It's in very good shape and was mummified naturally by the extremely dry climate. It was covered in straw over the leather wrapping and the straw and dry weather helped conserve it."

Previous find

The news of the find comes only days after another group of scientists announced the discovery of three mummified children apparently sacrificed to Inca gods. They were recovered from an icy grave 6,700m (22,000ft) up on Mount Llullaillaco, in the nearby Argentinean province of Salta.

This new baby mummy will now be subjected to carbon dating and DNA tests. These will establish many more details about its brief life and pin down a more precise age for the remains. Current estimates suggest the mummy is between 1,500 and 2,000 years old.

Carlos Aschero said he wanted to know more about the diet of the early inhabitants of the north of Argentina. Analysis of the mummy should help reveal such secrets.

"It could tell us whether the diet was based on meat or agricultural elements and indicate what the economy of the culture was based on," he said.