Both candidates in Romania's presidential election claimed victory on Sunday.  Most exit polls showed leftist challenger Mircea Geoana with a slim lead over centre-right incumbent Traian Basescu.   

The rival claims raised the prospect of a disputed outcome to the bitterly fought contest that could rattle the recession-stricken country's markets. Official results are due today at the earliest.    

Analysts say the vote was one of Romania's most important since the fall of communism 20 years ago. That's because the winner must steer long-delayed reforms that could decide whether the country can become closer to the richer West.

The winner must appoint a new prime minister to replace a Basescu-allied cabinet toppled by opposition lawmakers in October. He will then need to quickly enact a 2010 budget to release IMF aid.

Geoana has pledged to end a political deadlock and an economic crisis. He offered the prospect of greater stability but less reform.

Basescu backs the IMF's belt-tightening proposals, saying they are crucial for the European Union newcomer to claw back from an expected 8 percent economic contraction this year.