One of China's most famous tourist attractions, the 2,200-year-old terracotta army, is facing a new enemy - 40 types of fungi.
More than 1,400 of the life-size soldiers and horses, one of the greatest archaeological discoveries of the 20th century, are infected with mould, the State-run China Daily reported yesterday.
The authorities in the north-western city of Xian have called in a Belgian company which specialises in treating fungi to stop the rot before it spreads to all of the 7,000 terracotta warriors unearthed so far.
"Because of the diversity of the moulds it is difficult to kill all of the species without professional help," said Mr Wu Yongqi, curator of the museum, where the statues of archers, infantrymen, charioteers, horses, and even acrobats are housed in an underground vault.
Beijing sees the life-size army, which was built to protect the country's first emperor, Qin Shihuang (259-210 BC), as an important historical symbol. It is invariably included on the itinerary for visiting foreign dignitaries.
The three-year research and treatment programme may involve the use of 500 kg of chemicals.
Mr Paul Janssen, founder of the Belgian company, Janssen Pharmaceutical NV, said 90 per cent of the fungi on the terracotta warriors could be treated with existing chemicals. A company spokesman denied the treatment would harm the them or their visitors.
It was not immediately clear to what extent China's rapidly worsening air quality had contributed to the spread of the fungi. China has nine of the world's 10 most polluted cities and much of Xian is now a grimy industrial sprawl.
Chinese archaeologists have so far refrained from opening the adjacent site of Qin Shihuang's actual tomb, which is said to be full of treasures. They fear the damage which the city's pollution could cause the tomb.