Turkish authorities have detained nine journalists who covered overnight protests in several cities against the arrest of Istanbul Mayor Ekrem Imamoglu, the Journalists Union of Turkey said on Monday.

It was not immediately clear why the journalists were detained.

A Turkish court on Sunday jailed Istanbul Mayor Imamoglu, President Tayyip Erdogan's main political rival, pending trial on corruption charges in a move that triggered the country's biggest protests in more than a decade.

Despite bans on street gatherings in many cities, mostly peaceful anti-government demonstrations were held for a fifth night in a row on Sunday.

The main opposition Republican People's Party (CHP) have been calling for protests against the court decision on Imamoglu, which they label as politicised and undemocratic.

The government denies that the investigations are politically motivated and says the courts are independent.

Imamoglu has denied the charges he faces as "unimaginable accusations and slanders" and called for nationwide protests.

In an address to the demonstration in Istanbul's Sarachane district in front of the municipality building, CHP leader Ozgur Ozel said on Sunday that they would continue the protests until Imamoglu is released.

An Agence France Presse (AFP) staff photographer is among the detained journalists, the union said in a post on X.