Few doubted who was really in charge and in 2012 Mr Putin returned as president, this time for a term of six years.

If and when he reaches the end of his fourth term in 2024, the 65-year-old will have been in power for nearly a quarter of a century.

That would still fall short of Soviet dictator Joseph Stalin's 31 years in power or, indeed, the reigns of some Russian tsars such as Alexander II (26 years) and Nicholas I (30 years).

Spy turned president

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1952: Born 7 October in Leningrad (now St Petersburg), Russia's second city, studies law and joins KGB secret police, serving as spy in communist East Germany

1990s: After serving as top aide to mayor of St Petersburg, enters Boris Yeltsin's Kremlin in 1997, where he is made chief of the FSB (the KGB's successor)

1999: Appointed prime minister, becomes acting president upon Yeltsin's resignation

2000: Elected president and serves two four-year terms

2008: Barred from running for a third consecutive term, stuns analysts by returning to post of prime minister while his protege Dmitry Medvedev becomes president

2012: Re-elected president and for term of six years, under new law

2018: Re-elected for fourth term

How has Russia changed under Putin?

Ordinary Russians welcomed the stability associated with Mr Putin's early years in office when inflation was reined in and basic state functions like the welfare system were shored up.

Separatist violence in the North Caucasus which had plagued the administration of Mr Putin's predecessor, the late Boris Yeltsin, was finally brought to a bloody end.

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As prosperity grew, fuelled by oil and gas revenue, Mr Putin oversaw an increase in state power, rolling back independent media as well as political freedoms.