For the first time in years, Vladimir Putin has cancelled several public appearances due to illness - prompting speculation about the long-term durability of a leader feted for his virility.

On Monday, there was no visit to Sochi. Today, there was no discussion of microelectronics in the Kremlin. Tomorrow, the President will not make an appearance at the "Mentor 2018" forum in Moscow. And next week, he will not travel to the Russian Far East.

During his last public appearance, at the culmination of the Kremlin's "Leaders of Russia" talent competition, the President showed obvious signs of illness. His voice was weak and crackly and he coughed throughout. The Independent saw a similar picture when it accompanied Mr Putin on a campaign visit in Siberia last week. The President struggled with public speeches, made mistakes and seemed unfocussed.