A drawing of Tintin and Snowy from his adventure in Tibet

Paris, Nov. 22: He made him the world’s most famous Belgian and helped him sell 200 million copies around the world to date, but Tintin’s creator admits in previously unseen letters that the plucky cartoon character and his dog Snowy made him “sick”.

Hergé’s startling confession is just one of the revealing insights into his private thoughts, including love declarations to his first wife and a guilty admission of adultery, in letters showing the hidden side of the legendary artist.

Three hundred of them went under the hammer yesterday along with almost a thousand story boards, albums, statuettes and drawings at the Artcurial auction house in Paris. Most are written by Hergé — the nickname for Georges Remi — to his first wife Germaine Kieckens, his family and agent.

The letters were sold for 112,000 euros (£95,000) — around ten times the 10-15,000 euros (£8,500 to £12,700) they were expected to fetch — to the Jean-Claude Vrain book shop in the French capital.

Starting with a postcard to his parents from a boy scout’s camp in 1921 — when he was just 14 — the correspondence charts the highs and lows of Hergé’s creative and love life up until the early 1950s.

Carefully kept by Hergé’s nephew, Georges Remi Jr, they show how the boyish enthusiasm he shared with his famous cartoon reporter turned at times to ennui and doubt.

“I’m so tired,” he wrote in 1947, shortly after the war — Hergé’s career was tainted with links to Nazism, as he continued to publish his cartoons during the war in a Belgian newspaper used for collaborationist propaganda.

“There is a complete divorce between what I think and what I invent and draw,” he writes afterwards.

“And right now, my work makes me sick,” he tells his wife. “Tintin is no longer me. And I must make a terrible effort to invent (him)... If Tintin continues to live, it is through a sort of artificial respiration that I must constantly keep up and which is exhausting me.”

Many of the letters are touching love correspondence to Germaine, who he courted for months before finally marrying in 1932.

In one accompanied by a self-portrait of Hergé kissing his future wife in 1926, he writes: “I would like to say that when I think of you I melt with tenderness, that life without would be a monstrous thing. And I kiss you and hold you tight to me, so tight you cry... and I break a strap of your pretty pink outfit!”