Officials at Cambodia’s Angkor Wat have been accused of damaging the ancient site by installing light bulbs.

Visitors earlier this week claimed they saw chunks of masonry dislodged from the main Angkor Wat temple as holes were drilled in the stone. The work is part of a programme intended to illuminate the complex and enable more night tours to be operated.

Most visitors leave the sprawling Unesco-listed site at sunset, but recently a Korean company, Sou Ching, has started running limited nocturnal tours, and a number of lights have already been installed.

If plans to extend the tours go ahead, the complex would be open until 8.30pm, potentially thinning out the crowds during the day. Over half a million foreigners are expected to visit Angkor this year, which is by far Cambodia’s biggest tourist draw.

We want tourists to see all views of the temple, even in the dark places where they may have not have seen some of the sculptures and statues, said Bun Narith, head of Apsara, the agency that manages the temples. After a number of tourists complained, he denied the lighting installation was damaging the thousand-year-old complex, saying the lights were fitted into existing holes.

Angkor was removed from the Unesco ‘World Heritage in Danger’ list in 2004, but conservationists remain concerned for its welfare. In the last decade, hotel development and tourist numbers have soared, swelling the local population and causing potential subsidence by lowering the water table in the area.

Apsara and Unesco will meet next week to “evaluate the impact of using light at night at the temple site”, said Narith.