Russian tycoon Mikhail Prokhorov, who has said he will stand against Vladimir Putin in next year's presidential elections, is one of his country's richest men and owner of the New Jersey Nets basketball team.
Mr Prokhorov is the billionaire founder of the Onexim Group, which has a wide variety of interests, with gold and nickel mining at their core, and is ranked by Forbes as Russia's third richest man with a fortune of around $18bn (£11bn; 13bn euros).
He had stayed out of politics until a few months before December's parliamentary elections, but then became leader of the Kremlin-backed liberal Right Cause party. Within weeks he had resigned, alleging Kremlin interference.
It is his earlier closeness to the Kremlin that has prompted some Russian political figures to suggest he has come forward to challenge for the presidency merely to provide liberal voters with a candidate and to draw attention from recent anti-Putin protests.
