Tunisians have lined up at polling stations to vote in their North African country's first free and open presidential election.

Sunday's vote marks the long awaited completion of a rocky transition to democracy after Tunisians electrified the region by overthrowing dictator Zine El Abidine Ben Ali in 2011, kicking off the Arab Spring pro-democracy uprisings.

The front runner among the nearly two dozen presidential candidates is 87-year-old Beji Caid Essebsi, a veteran politician from the previous regime who has gained people support with talk of a return to stability after years of economic and political turmoil.

If no candidate gains an outright majority, the vote will go to a run off held in one month.

Alone among the countries of the Arab Spring, Tunisia's transition has remained on track.