Alexander Lebedev pledges support for Russian opposition activist Alexei Navalny

Alexander Lebedev threw his support behind the Russian opposition activist Alexei Navalny yesterday, offering him backing in any future presidential bid.

Speaking at the think-tank Chatham House, the financial backer of The Independent said that the man who led the protests in Moscow against the re-election of President Vladimir Putin would have his support as long as he was standing in free and fair elections. "Yes, I would support him, but if he decides to run alone, he has to be challenged by someone."

Mr Navalny, a lawyer who rose to prominence as an opposition blogger, is one of Russia's most promising opposition leaders after exposing corruption in Moscow's political classes.

He is said to be the opposition figure feared most by the Russian leader. Last December he was detained for several days after being arrested during an opposition rally; two weeks ago his flat was raided by police ahead of another planned march. Mr Lebedev's support for any Kremlin bid comes after he offered backing to Mr Navalny's Foundation for Fighting Corruption.

Mr Lebedev is one of several wealthy Russians, known as the "16 brave ones", who have offered financial assistance to organisations supporting a crackdown against corruption. Vladimir Ashurkov, executive director of the Navalny foundation, said that the persecution of opposition figures had worsened since Mr Putin's re-election.

"No doubt, the system in Russia will change," Mr Ashurkov said. "It may take six months, or six years, but the situation will change. Since the election, the crackdown has intensified, but we believe in what we do, and will not stop – it is the only way."

Mr Lebedev used the event to lay out his anti-graft manifesto and called for international support – involving Europe, the US, China and Russia – to tackle the issue. He warned that illegal and embezzled funds would total $12trn (£7.6trn) over the next decade.

"Just imagine that amount of money sitting somewhere beyond any controls of central banks, or politicians even being aware of it – nobody at the G20 was discussing that," he said.

"I was... still hoping that President Putin would come up [with] an initiative – since Russia is now hosting the G20 – to organise an international board with special powers to fight global corruption – alas, it hasn't been achieved."