Independent law professor Kais Saied looked set to win Tunisia's presidential runoff, as exit polls forecast an overwhelming victory against his rival.

Polls carried in Tunisian media on Sunday projected that Saied would win between 72 and 77 percent of the vote.

His opponent Nabil Karoui who was in jail for most of the campaign was forecast to win between 23 and 27 percent.

The publication of the exit polls triggered celebrations at Saied's election campaign offices in central Tunis, as fireworks were set off outside and supporters honked car horns.

The turnout stood at 38.2 percent three hours before the voting ended, the electoral commission said at a news conference, adding that the participation was higher than that of last week's legislative elections.

About 7.2 million people were registered to vote in more than 4,500 polling stations across the country.