Russia denied that it has built a military base inside a zone that holds the UNESCO world heritage site in the ancient Syrian town of Palmyra.
The Russian military on May 17 described the camp as "temporary," saying its few housing units were being used by explosives experts who are removing mines left behind by Islamic State militants.
It said the Syrian government had given approval to build the camp, which includes a field hospital and bakery used by local residents.
The head of Syria's antiquities department, who noted the town's priceless antiquities are safer thanks to the Russian presence, nonetheless told the Associated Press that he would not have granted Russia permission to build the camp if he had been asked.
A UNESCO official said it was unclear whether the encampment was in a buffer zone to the archaeological site, but said it does not pose a threat to the historic area.
Syrian troops backed by Russian air strikes captured Palmyra in March and fighting continues nearby.
Russian demining experts have found and detonated hundreds of bombs left behind by IS at and near the site since the town was recaptured.