In Agatha Christie’s works, which languages does Hercule Poirot speak, in addition to French and English?

Anyone who reads one of the many “Poirot” novels knows that the famous fictional detective speaks French: the mainly English dialogue is peppered with phrases such as “Eh bien”, “mon ami”, “que je suis bête”. Could Agatha Christie’s clever detective speak any other language?

There is reason to suspect that he could. Hercule Poirot is, of course, not French: he is Belgian. Belgium has three official languages, Dutch, French and German. Do the novels reveal any knowledge of the other Belgian languages?

While there is no evidence in the novels that he can speak Dutch, there is evidence that he can speak German. In "Murder on the Orient Express", he conducts interviews with the passengers in three languages one of which is German. In the novel "The Clocks", Poirot uses his knowledge of the construction of the German language to clear a certain English-speaking (but actually German) couple from suspicion.

In addition, there is evidence that Poirot could speak Italian, but not from Agatha Christie’s original novels. Agatha Christie also wrote a play, “Black Coffee” (1930) in which Poirot chats to a Dr. Carelli in Italian. “Black Coffee” was reissued as a novel after Christie’s death.