Afghan President Hamid Karzai has criticized demands by opposition candidates to stop Saturday's presidential elections and hold them again because of fraud.

Mr. Karzai said it was too late to call for a boycott now that millions of Afghans turned out to vote despite rain and snow. He said the people's will must prevail.

Electoral officials also rejected the demand as unjustified. They said despite some technical difficulties, Afghans have turned out in large numbers and the process has been safe and orderly.

The controversy erupted after some polling stations mistakenly used regular ink, that could be easily washed off, to mark the thumbs of people who had voted. Election officials said the problem was caught quickly and would not invalidate the overall vote.

Long lines formed early at polling stations across Afghanistan with many voters expressing delight at being able to directly choose their leader.