Election chiefs said last month Kasyanov could not run because signatures he submitted in support of his bid were forged. He accused the Kremlin of barring him to slant the vote in favor of front-runner Dmitry Medvedev.

Kasyanov, a former prime minister, had no chance of winning the March 2 election but his removal from the ballot has fuelled criticism that the Kremlin will brook little real opposition.

In a judgment after a one-day hearing, the Supreme Court said it had decided to leave the Central Election Commission decision to bar Kasyanov unchanged and to reject an appeal submitted by his lawyers.

Yelena Dikun, a spokeswoman for Kasyanov said: "The Central Election Commission ignored the views of citizens ... and now the Supreme Court, which is part of the same system, has also ignored the views of citizens."

Russian President Vladimir Putin is constitutionally barred from seeking a third consecutive term. He has endorsed Medvedev, a 42-year-old first deputy prime minister, to replace him.