The auction house Christie's defied Beijing yesterday by selling off two art objects that China believes were looted from an imperial palace 140 years ago.
The two sculptures - a monkey head and an ox head - fetched HK$15.93 million (£1.32m), compared with Christie's earlier estimate of between £290,000 and £370,500.
Christie's said both pieces had gone to the same buyer, believed to be a collector from mainland China. Several Hong Kong activists tried to storm the auction venue at a five-star hotel, scuffling with police and security staff.
A hexagonal vase and a bronze tiger head are due to go under the hammer at a Sotheby's auction there on Tuesday.
China believes all four treasures were looted from the Yuan Ming Yuan, the Manchu emperors' summer palace outside Beijing, when it was ransacked by British and French troops in 1860. The site is a ruin to this day.
The Treaty of Beijing was signed days after the sacking, ceding to Britain the tip of the Kowloon Peninsula on the Chinese mainland. Three years after Britain handed back Hong Kong and Kowloon to China, Beijing sees the sale of its "looted" art as an affront to national pride.
"If the auction houses insist on selling these treasures, they will pay for their ill-advised choice," said Liu Shugung of China's state bureau of cultural relics. He declined to say what action China might take.