In a sudden move, Vladimir Putin has dismissed his chief of staff, Sergei Ivanov, who has been one of the Russian president’s most trusted allies throughout his years in power since 2000, serving in several key positions including defence minister.

In a statement published on the Kremlin website on August 12, it was announced that Putin had "decreed to relieve Ivanov of his duties as head of the Russian presidential administration", but gave no reason. Ivanov's deputy since 2012, Anton Vaino, has been appointed as his successor.

According to the BBC, both Putin and Ivanov later appeared on Russian TV explaining that Ivanov had asked to leave the post, and recommended that Vaino should replace him. But despite the smiles for the cameras, questions are being asked about the real reason, especially given that the country faces crucial parliamentary elections in September.

Ivanov, who served with Putin in the Soviet-era KGB spy agency, was appointed Kremlin chief of staff in late 2011, only months before Putin’s 2012 re-election as president.

Many observers had regarded Ivanov as a leading candidate to take over from Putin as president when his second term ended in 2008, but instead Putin handed the top job to Dmitry Medvedev, the current prime minister, before reclaiming it in 2012.

A polished man known for his love of ballet and opera, Ivanov cut an intriguing figure in Putin's circle, especially when set against the more thuggish characters of the so-called siloviki – those with close ties to the security services who populate the Kremlin – such as Igor Sechin, who has been called Russia's "Darth Vader" and the "scariest man on Earth".