Work is urgently being carried out in southern Peru to prevent floods from damaging the Nazca lines, an ancient series of geometric forms and animal figures carved into the desert.

Following unseasonal heavy rain, several of the 16 mysterious drawings have been hit by mudslides, and workers are constructing drainage ditches to prevent further damage.

So far, the floods have not affected the most famous figures - etched into the desert sands by the Nazca Indians between 300-600 AD - which include a hummingbird, monkey, heron, whale, spider and flower.

Situated some 400 kilometres (250 miles) southeast of the capital, Lima, near the city of Nazca, the lines are one of Peru's main tourist attractions.

Their size and complexity have baffled archaelogists, who wonder how such straight lines and precise figures discernible only from the air could have been constructed without modern tools or aircraft.

Scientists suggest the giant figures may have been used to help measure time or map underground water supplies.

They were threatened by similar landslides in 1998, when El Nino rains inundated the southern desert.

In the same year, at least three of the figures were damaged by tourists in a four-wheel drive vehicle.