Turkish authorities have detained President Recep Tayyip Erdogan's chief political rival, Istanbul Mayor Ekrem Imamoglu, as part of an investigation into corruption and terror links, according to media reports.

The state-run Anadolu Agency said prosecutors also issued warrants for around 100 other people, including businessmen and journalists. 

Imamoglu said in a social media post early Wednesday that hundreds of police were in front of his house.

Broadcaster CNNTurk reported that police forces were searching his property as part of a probe.

Imamoglu's press aide was later quoted by the AFP news agency as saying the mayor "was detained and is now at police headquarters."

Authorities have banned demonstrations in Istanbul for four days in an apparent effort to prevent protests following the arrest. The Netblocks internet observatory also said early Wednesday that Turkey had restricted access to multiple social media platforms.

Imamoglu's detention comes a day after Istanbul University announced it was revoking his university diploma over irregularities — dealing a major blow to his ambition to run for president in the country's next election.

To run for president, a candidate must have a university degree. 

The university said it was declaring the graduations and degrees of 28 people, including Imamoglu, as being "void" because of "obvious error."

Imamoglu, a popular opposition politician from the center-left Republican People's Party (CHP), was set to be nominated as his party's pick for presidential candidate this weekend.

Imamoglu has been twice elected mayor of Istanbul, in 2019 and 2023, beating candidates from Erdogan's ruling conservative Justice and Development (AKP) party.

The mayoral race in Istanbul has particular resonance since Erdogan launched his political career there, serving as mayor in the 1990s.

Erodgan has dominated Turkish politics since becoming prime minister in 2003 and must hold elections before they are scheduled in 2028 if he wants to run again under the constitution. 

In a post to his X account, Imamoglu said he would not give up.

"The will of the people cannot be silenced through intimidation or unlawful acts," he wrote. "I stand resolute ... I stand firm in my fight for the fundamental rights and freedoms."

CHP chairman Ozgur Ozel denounced Imamoglu's detention, saying it amounted to "an attempted coup against our next president."

Edited by: Wesley Dockery and Louis Oelofse