Ekrem Imamoglu is seen as the main rival of Turkey's president Recep Tayyip Erdogan.

He was arrested just hours before he was scheduled to be selected as the Republican People's Party's (CHP) 2028 presidential nominee through voting.

Police reportedly resorted to using tear gases and rubber bullets to disperse the crowd that had assembled to demonstrate against the arrest of the Turkish politician.

This is one of the worst political demonstrations Turkey has witnessed in a decade.

The main protest venue remained close to Istanbul's city hall where a large number of demonstrators were seen waving the Turkish flag and chanting slogans in front of the riot police.

Officers were seen firing water cannons at some protesters and using pepper spray, BBC reported.

The last post from the Istanbul Mayor's X handle said: "I send my greetings to the millions who demand justice tonight in Saraçhane and in the squares all around my country."

Another earlier post from his handle said voters have shown Turkey had 'enough' of Erdogan.

His Twitter handle claimed 15 million people cast a ballot on Sunday during the presidential election polls.

The CHP said some 1.6 million votes came from its members, while the rest were cast by non-members at separate ballot boxes for those who wished to show solidarity with Imamoglu, reported BBC.

The British media, however, clarified it did not verify the figures independently.

Meanwhile, the arrest will not prevent   Imamoglu's candidacy and election as president.

However, if he is convicted of any of the charges levelled against him then he will not be able to run the polls.

Erdogan will not be able to contest the 2028 polls due to term limits.

Degree Revocation

Ekrem Imamoğlu's arrest occurred just days after Istanbul University revoked his degree amid claims that he had falsely obtained it.

The Turkish politician called the university's action 'unlawful'.

He earlier wrote on X: "The decision of the Istanbul University Board of Directors is UNLAWFUL. They do not have the authority to make such a decision. The authority lies only with the Board of Directors of the Faculty of Business Administration."

Since the protest began on Wednesday following the initial detention of the leader, 700 people have been arrested in the country.