A hike in tourism to Peru's Machu Picchu has many conservationists concerned.

Because visits have doubled since 1998 to 800,000 people, UNESCO may add the pre-Columbian Inca site to its list of endangered World Heritage sites. Threats include landslides, fires and development.

UNESCO officials will discuss the situation at the World Heritage Committee meeting in Quebec City this week that was organized to determine which of the world's cultural treasures should be added to its list, and which sites already included are now threatened.

The village lacks adequate sanitation and Peru's government has done little to address landslide concerns, according to a UNESCO advisory report.

Machu Picchu was named a World Heritage Site in 1983.