A Russian businessman has placed a $1m bounty on Vladimir Putin’s head and urged the country’s military officers to bring the president to justice.

       Entrepreneur Alex Konanykhin made the promise in a post on social media site LinkedIn and called it his “moral duty” to take action and help Ukraine following the unprovoked attack.

       “I promise to pay $1,000,000 to the officer(s) who, complying with their constitutional duty, arrest(s) Putin as a war criminal under Russian and international laws,” wrote Mr Konanykhin.

       “Putin is not the Russian president as he came to power as the result of a special operation of blowing up apartment buildings in Russia, then violated the Constitution by eliminating free elections and murdering his opponents.”

       His post included a photo of Mr Putin, with the caption, “Wanted: Dead or alive. Vladimir Putin for mass murder.”

       And he added: “As an ethnic Russian and a Russia citizen, I see it as my moral duty to facilitate the denazification of Russia. I will continue my assistance to Ukraine in its heroic efforts to withstand the onslaught of Putin’s Orda.”

       The word “Orda” is Russian for “horde.”

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       Mr Konanykhin has a complicated history with the Russian government, and in 1996 was arrested while living in the US after Russian authorities claimed he had embezzled $8m from the Russian Exchange Bank.

       FBI agents testified that the Russian mafia had taken out a contract on Mr Konanykhin, and the case was settled and he was granted political asylum.

       His asylum was revoked several years later, but his deportation was eventually cancelled by US District Judge T S Ellis, who overruled it, who said that a decision to return him to Moscow “stinks”.

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       Mr Konanykhin’s reference to blowing up buildings relates to a conspiracy theory that the Russian intelligence service, the FSB – which Mr Putin was head of from 1998 to 1999 – was responsible for explosions in four apartment blocks in 1999 which killed about 300 people. The attacks, blamed on Chechen terrorists, helped spark the Second Chechen War, which itself helped consolidate Mr Putin’s popularity in Russia. He became prime minister in 1999 and was named acting president on the last day of the year, subsequently being elected to a full term the following March.

       The theory was expounded among others by former FSB officer Alexander Litvinenko, who was assassinated in London in 2006 – apparently by Russian agents – using the radioactive isotope polonium-210.