Thousands of protesters returned to the streets of Istanbul on Tuesday after a week of the biggest protests to hit Turkey in over a decade, defying a crackdown that has seen almost 1,500 arrested including an AFP journalist, the agency reports.

The demonstrations erupted after the arrest of the mayor of Istanbul Ekrem Imamoglu, the main political rival of President Recep Tayyip Erdogan, in a move opposition supporters see as a blatant violation of the rule of law.

The authorities have hit back with a crackdown that has alarmed rights groups, with seven journalists who covered the protests remanded in custody by an Istanbul court on Tuesday.

Among them was AFP photographer Yasin Akgul, drawing a sharp rebuke from the Paris-based news agency.

"His imprisonment is unacceptable. This is why I am asking you to intervene as quickly as possible to obtain the rapid release of our journalist," the agency's CEO and chairman Fabrice Fries said in a letter to the Turkish presidency.

The court charged Akgul, 35, and the others with "taking part in illegal rallies and marches", though Fries said Akgul was "not part of the protest" but only covering it as a journalist.

Media freedom group Reporters Without Borders (RSF) denounced the decision as "scandalous", with its Turkey representative Erol Onderoglu saying it "reflects a very serious situation in Turkey".

The journalists were among more than 200 people prosecutors have recommended for imprisonment pending trial, including left-wing activists rounded up at their homes in raids early Monday. By late Tuesday, 172 people, including the seven journalists, had been jailed ahead of trial.