A forest fire burning close to the main access route to Machu Picchu, Peru's best-known tourist site, has killed one person and injured two others, according to local authorities cited by the French news agency AFP.

The fire has been burning since Monday in the Sacred Valley of the Incas, in the Cuzco region of southern Peru. Miguel Osco, head of the regional disaster response office in Cuzco, told the radio station RPP that an elderly person died in the flames and two people suffered second-degree burns. No further details about the identities of the injured have been released.

The blaze is near Ollantaytambo, a town that is home to the busiest train station for visitors heading to Machu Picchu. Reports indicate the town itself is not threatened and that guided tours have been barely affected. Even so, a local resident, Gustavo Lozano, told RPP that the fire was very close to the main route. "Tourist buses are driving just a few hundred metres from the fire," he said.

The fire is thought to have started when farmers burned crop residues and weeds, a common practice at this time of year to clear farmland. Dry vegetation, plenty of sunshine and warm weather have helped the flames spread further than intended. "The vegetation is very dry, so the fire is spreading quickly," Osco said.

Machu Picchu is a 15th-century Inca citadel high in the Andes mountains. It was rediscovered by the outside world in the early twentieth century, long after the Incas abandoned it. With more than 1.5 million visitors a year, it is Peru's most important tourist destination, and the Sacred Valley serves as the gateway for most of those travellers.

Why this matters: the incident shows how traditional agricultural burning, combined with dry and hot conditions, can quickly turn into a danger to people and to areas that are vital for tourism. Authorities have not yet said how long the fire may continue or whether access to the site could be affected.