Brawls broke out at polling stations in the southern French city of Marseille on Monday, as Turks living abroad voted in pivotal elections back home.

Four police officers were reportedly injured trying to separate fans of the incumbent leader and those who oppose him.

The first fight occurred at around 2:30 p.m. local time, with four people hospitalized from the violence.

Officers later used tear gas.

Clashes continued throughout the day, despite the presence of police, and two people were arrested.

Elections in Turkey will take place on 14 May, but Turkey's large ex-pat community is being allowed to vote weeks before.

It is one of the most significant votes in years, which will shape Turkey's political destiny.

Erdogan, who has ruled the country for more than 20 years, is facing a united opposition for the first time since coming to office.

His support has been battered in recent years as Turkey's once-strong economy has hit the rocks, with the Turkish lira collapsing in value.

Meanwhile, some accuse the 69-year-old of taking Turkey towards authoritarianism and undermining the secular principles it was founded upon.

However, Erdogan retains high levels of support, especially among religious and more conservative voters, with polls predicting a tight race between him and his opponent Kemal Kiliçdaroglu.

The 74-year-old heads an alliance of six opposition parties, ranging from the nationalist right to the democratic left.

He is the head of the CHP founded by the father of modern Turkey, Mustafa Kemal Ataturk.

Kiliçdaroglu has vowed to expel the country's large Syrian refugee population of around 3.5 million should he win the election.

If both camps claim to win the first round, a possible second would be organized for 28 May.