Sotheby’s said it will hold a Chinese contemporary art sale in Hong Kong, an auction that could rake in almost $13 million as the city continues to draw wealthy Asian collectors.

About 100 pieces from re-nowned Belgian collector Baron Guy Ullens will go under the hammer on April 3, Sotheby’s said, adding that most of the collection from the 1980s onward had rarely been seen in public since their acquisition.

A few days later the auction giant will hold another sale featuring about 80 lots of Imperial Chinese porcelain, expected to fetch about $121 million.

Sotheby’s described the Ullens pieces as “one of the most important and comprehensive assemblages of contemporary Chinese art created to date” by well-known artists including Zhang Xiaogang.

Zhang’s triptych Forever Lasting Love is expected to fetch $3.2 million, it said.

“The essence of The Ullens Collection is the visualisation of the Chinese nation’s history through works of art,” said Evelyn Lin, Sotheby’s head of contemporary Asian art.

Hong Kong has emerged as the world’s third-largest auction centre after New York and London, thanks in large part to China’s rapidly growing number of millionaires.

Mainland Chinese are regular buyers of the top lots at sales of art, jewellery and wine and Hong Kong has positioned itself as the gateway to China’s vast market.