The last polling stations closed at 1400 GMT in the west of the country and the first estimates were expected to be released late on Sunday.

The election took place against the backdrop of raging inflation and massive devaluation, with the uncertainty weighing down on many voters, AFP correspondents reported.

"Everyone is worried about the day to day" 43-year-old Guler Kaya said at an Istanbul station.

"The crisis is swallowing up the middle class, we have had to change all our habits," she said. "If Erdogan wins, it will get even worse".

"When Turkish people vote, the situation in the kitchen or on their plate changes the voting trend," Ali Faik Demir, a political scientist at Galatasaray University, told AFP.

Vote change happens "when we cannot afford a living, when we cannot eat", he said.

Erdogan may not have been a candidate in the municipal vote, but he dominated the campaign.

His road to power in Turkey began in Istanbul when he was elected mayor of the mythic city straddling Europe and Asia in 1994.

His allies held the city until five years ago, when Ekrem Imamoglu of the secular Republican People's Party (CHP) wrested control.

If Imamoglu retains his seat, he will likely be the main opponent to Erdogan's ruling AKP party in the next presidential elections in 2028.

As soon as Erdogan clinched re-election as president last May -- he has held the position since 2014 -- he launched the battle to reclaim the city of 16 million people.

"Istanbul is the jewel, the treasure and the apple of our country's eye," the 70-year-old leader said at a recent rally in the city.

- More than a mayor's race -

In Istanbul, Turkey's economic powerhouse, the president named former environment minister Murat Kurum as his mayoral candidate, painting Imamoglu as a "part-time mayor".

"This election will mark the beginning of a new era for our country," Erdogan said after casting his vote in Istanbul at midday on Sunday.

"Whoever wins Istanbul, wins Turkey," Erman Bakirci, a pollster from Konda Research and Consultancy, recalled Erdogan once saying.

In the run-up to the election, Imamoglu has defended his record and has focused on local issues: "Every vote you give to the CHP will mean more metros, creches, green spaces, social benefits and investment."

- 'Emotional day' -

After casting his vote with his wife and two sons in Istanbul around midday Sunday, Imamoglu emerged to supporters applauding and chanting "Everything will be fine", his 2019 election slogan.

"I hope that... the will of the ballot box will be expressed without harm to anyone, whatever the result is, whoever our citizens voted for," Imamoglu said in the garden of a school polling station.

"Today is an emotional day for me", he said, adding that he was trying to ensure "equality without prioritising partisanship".

The election is being held with inflation at a whopping 67 percent and with a massive devaluation of the lira, which slid from 19 to a dollar to 31 to a dollar in one year. Analysts say this could work in favour of the opposition.

"We are doing our best to ensure that young people, women and mothers have the best possible life," he said.

Armed clashes were reported from a village in Turkey's Kurdish-majority southeast, leaving one dead and 12 wounded, a local official told AFP.

- Fractured opposition -

Some 61 million voters are picking mayors across Turkey's 81 provinces, as well as provincial council members and other local officials.

The opposition has been fractured ahead of the polls, in contrast with the local elections five years ago.

This time around the main opposition party, the social democrat CHP, has failed to rally support behind a single candidate.

Its candidates are narrowly favoured in Istanbul, as well as in the capital Ankara and the Aegean port city of Izmir, though analysts have warned that opinion polls have not always been accurate in the past.

In the capital Ankara, retiree Meliha Sonmez sounded a warning as she prepared to vote: "If Erdogan loses the ballot, he will be weakened."

Polls opened at 0400 GMT in the east and closed at 1400 GMT in the west, including Istanbul.