text: The portraits immortalised the founder of China's Communist Party as a pop art commodity in the vein of Warhol's Marilyn Monroe  and Campbell soup.
  Based on a photo in Mao's Little Red Book, the portrait series is among the most famous images of the 20th Century.
  The auction of this work is expected to fetch as much as $15m (£12.1m).
  This particular Mao portrait was sold in 2014 in London for £7.6m ($9.4m)  and the current owner, who is not identified, has now put it up for sale with Sotheby's in Hong Kong,  with the auction expected on 2 April.
  Warhol began his series of silk-screen portraits of Mao in 1972 when ties between then cold-war foes China and US began to thaw after the historic trip to Beijing by US President Richard Nixon.
  The photograph that Warhol used for the portrait was one that adorned the inside cover of the so-called Little Red Book, itself an symbol of Chinese communism and a work of propaganda.
  More than a billion copies are thought to have been published, making the book one of the most widely produced of all time.
  During Mao's reign it became virtually mandatory to own and carry a copy.
  Warhol's Mao series led to almost 200 portraits in similar versions and sizes and follows the artist's similar earlier works on Marilyn Monroe and Elvis Presley in the 1960s.
  Picking Mao was a departure from his trademark of elevating a banal commodity  (as he did with Campbell soup) or illuminating glamour (as he did with Marilyn Monroe).
  Chairman Mao was a political leader both deeply revered and feared and certainly an unlikely subject for the bold colour contrasts of the Pop Art movement.
  But it remains a delicate issue in China to this day. In a 2013 exhibition, the first comprehensive survey of Warhol's art in China, the Mao portraits were nowhere to be seen.
  The debate in Chinese media at the time was around whether the images were showing respect or mockery.
  Yet  Chinese investors are increasingly buying Western art. They are thought to make up one fifth of the world's buyers of art.
  Downward pressure on the yuan and caps on capital outflows are only adding to the appetite for investing on the global art scene.
  So Warhol's portrait of China's former Communist leader may yet find its way to China through the workings of global capital markets.
  Reporting by the BBC's Andreas Illmer.
target: An Andy Warhol painting of Chairman Mao is to be auctioned in Hong Kong - and it could go to a Chinese bidder for a "homecoming" of sorts.