BEIJING, Oct. 28 (Xinhua) -- China plans to lay down a red line on carrying capacities to cope with potential overtourism at its grotto relics, said heritage and tourism authorities.

Heritage and tourism authorities across the country are asked to conduct careful studies and determine rigorous capacities for these sites, according to a notice issued by the National Cultural Heritage Administration and the Ministry of Culture and Tourism.

Strict gauges need to be set for core areas, individual caves, and cliff paths at grotto sites, the notice added.

The notice listed an array of measures to help control visitor levels, including online reservations, digital ticketing, and staggered visiting times.

Management teams of grotto relics are also encouraged to create digital versions of museums, develop smart relic sites, and introduce VR services to deal with tourism pressure.

Data show that there are a total of 5,198 grotto temples in China. Among them, 142 are under national-level protection, and 345 are under provincial-level protection.

Including the Mogao Grottoes, Yungang Grottoes, and Longmen Grottoes, ten of the historical relics are inscribed on the UNESCO World Heritage List.