NESTLED between the headwaters of the Magdalena river and high Andean moorland, the ancient stone statues at San Agustín are among the most mysterious pre-Columbian archaeological artefacts. So far archaeologists have discovered 40 large burial mounds containing 600 likenesses of mythical animals, gods and chieftains in what is South America’s largest complex of megalithic statues. Like other sites in the region, San Agustín has suffered plunder, both organised and freelance. Konrad Preuss, a German anthropologist who led the first European excavations there, shipped 35 statues that he found to a museum in Berlin, where they remain.

This history has made the local inhabitants, who live from tourist visits to the site, suspicious. So it proved with a plan by the national museum to take 20 of the statues to the capital, Bogotá, a ten-hour drive away, for a three-month exhibition to mark the centenary of Preuss’s discovery of the site.

Aware of the sensitivity of removing the statues even temporarily, anthropologists from the Colombian Institute of Anthropology and History held town meetings to explain the importance of allowing them to be seen by a wider public. But the locals said they worried that the objects would not return, or would be swapped for replicas. They claimed that moving them would upset their spiritual energy. As the date for the exhibition neared, they began making demands, such as asking for a new drinking-water system for the town in exchange for letting the statues go.

No deal was agreed. On the day last month when the sculptures, carefully wrapped and crated, were to travel to Bogotá, locals backed by outside agitators blockaded the road and prevented workers from loading the trucks. The anthropologists backed off. “It never crossed our minds that they wouldn’t trust us with the statues,” says María Victoria de Robayo, director of the national museum, which has held temporary exhibitions of Greek urns loaned by the Louvre and of China’s Terracotta Warriors.

The museum has adopted its own form of protest. The exhibition opened, minus statues, on November 28th. “We wanted the public in Bogotá to perceive the absence,” Ms De Robayo says. So light is projected where the statues would have been; guides use a virtual-reality program and tablet computers to show visitors a 3D image of what was meant to be there. This is unlikely to draw the crowds, but the affair has sparked a debate about Colombia’s cultural heritage. The museum has taken a robust position: the opening display invites visitors to consider “the emptiness and silence that emerge when a few people claim exclusive right over our heritage, trampling the cultural liberties of all Colombians.”