Xi Jinping thanked Vladimir Putin and said that in China, Putin was extremely popular. (AFP photo)

Chinese President Xi Jinping celebrated his 66th birthday on Saturday with Russian President Vladimir Putin, who Xi considers a close friend and who gave Xi ice cream as a present, Chinese state media reported.

The discussion of senior leaders' private lives is extremely rare in China, and the exact birth dates of most of them are not revealed publicly, as they are considered a state secret.

State television showed pictures of Xi and Putin holding up champagne glasses to toast Xi's birthday at the hotel he is staying at in Dushanbe, the capital of Tajikistan, where they are both attending a regional summit.

While Putin gave Xi Russian ice cream - the flavour was not mentioned - Xi gave Putin back some Chinese tea, the report said.

Xi thanked Putin and said that in China Putin was extremely popular, it added.

Pictures on Chinese state television's website showed the two men inspecting a white cake decorated with red and blue confectionary flowers with the words written on it, in somewhat shaky red-coloured Chinese characters, "good fortune double six".

It was not immediately clear if Xi ate any of the cake.