Russian billionaire Mikhail Prokhorov has said he will challenge Prime Minister Vladimir Putin in next March's presidential election.

俄罗斯亿万富翁米哈伊尔·普罗霍罗夫称，他将在明年三月份与总理普京竞争总统一职。

Mr Prokhorov is one of Russia's richest men
Mr Prokhorov said it was "the most serious decision" of his life.

Saturday saw Russia's biggest demonstration¹ in years by protesters calling for fresh parliamentary polls over alleged² voting fraud.

Mr Putin's party, United Russia, barely scraped a majority in the elections held earlier this month.

"I have made the most serious decision of my life. I am running for president," Mr Prokhorov said at a news conference.

Mr Prokhorov said he would not build his presidential campaign on criticism of Mr Putin.

"Criticism must make up no more than 10%… I would like to focus on the things I would do," he said.

Power struggle

Earlier this year, the metals billionaire and owner of the US NBA New Jersey³ Nets basketball team made a short-lived effort to challenge the United Russia party in this month's parliamentary elections.

He later resigned from his own party, the Right Cause party, following an internal power struggle that he blamed on the Kremlin.

He then accused Kremlin strategist Vladislav Surkov of being linked to the party's split and said he would push for Mr Surkov's dismissal.

On Monday, he said: "I have found a more sophisticated way [to dismiss Surkov], I think I should just become his boss," Mr Prokhorov said.

In a recent blog, Mr Prokhorov said he saw no alternative to Mr Putin as president.

"Whether they [Russian people] like it or not, Putin is so far the only figure who can manage this inefficient⁴ state machine," Mr Prokhorov said.

Mr Prokhorov is ranked by Forbes as Russia's third richest man with a fortune of around $18bn (£11bn; $13bn euros).