Tintin comic books have sold millions of copies around the world.

A rare drawing of comic book hero Tintin by Belgian cartoonist Hergé fetched over a million dollars at auction in Hong Kong Monday as experts say comic art is becoming as collectible as paintings.

The artwork is an illustration from the cartoonist’s “The Blue Lotus” book, published in 1936, which sees Tintin and sidekick Snowy the dog on an adventure in Shanghai.

It sold for HK$9.6 million ($1.2 million) and French auction house Artcurial said it had been bought by an Asian collector.

Drawn in monochrome, it shows Tintin being pulled along a street in a rickshaw with a policeman looking on. The drawing is the only original from the book to remain in private hands with the rest in museums, Artcurial said.

“’The Blue Lotus’ is considered by specialists as the masterpiece album of Herge,” said Eric Leroy, Artcurial’s expert in comic strips.

“The design and drawing of Herge had become mature… It was also unusual to talk about China in the thirties in Europe.”

The piece had been predicted to sell at between HK$8.6 million and HK$13 million.

The record for a Tintin piece was set by a 1937 comic strip sold at an Artcurial auction in Paris in May for $3.4 million. It was bought by an American collector.

Despite a downturn in the Chinese economy which some fear will dent the region’s burgeoning art market, auction houses in Hong Kong say they are still optimistic that rare pieces will sell.

It will hold two evenings of auctions Monday and Tuesday, featuring everything from paintings by Picasso and Renoir to bags by Hermès and a Mercedes Benz 300 SL Roadster.

Alongside the Hergé drawing contemporary European pieces from leading comic artists Enki Bilal, Moebius and Nicolas de Crécy were also on sale.

“Modern comics are like a painting — it’s like modern art,” says Leroy.

Two of the comic artworks broke records for sales by the artist Monday, with a Bilal piece fetching HK$2.3 million and a Moebius going for HK$2.4 million.