The world famous cave paintings at Dambulla Temple are being threatened by a fungi infection.
As a last resort to prevent an escalation of the threat, a limited number of visitors will be allowed at a time to the world heritage site.
Director general of the Central Cultural Fund Prof. Gamini Ranasinghe has told BBC Sinhala Service that damage-repair work was now under way.
Digital copies of the paintings are being taken for preservation, he said.
UNESCO is due to send an expert shortly to help in the work.
The cave temple with 160 statues of Lord Buddha, Bodhisattva and gods, also has wall paintings in a 20,000 square feet area.
