Heraldo de Madrid - Protests resume as Istanbul mayor spends first night in custody

Ekrem Imamoglu, who is President Recep Tayyip Erdogan's main political rival, was detained by hundreds of police before dawn on Wednesday, four days before being named as the main opposition CHP's candidate for the 2028 race.

The move sent Turkey's financial markets into a tailspin, dealing a heavy blow to the Turkish lira that was trading at around 38 lira to the dollar on Thursday.

Turkey's Central Bank said it would draw on its foreign exchange reserves if needed to prevent further harm to the lira, with economists saying it had already done so on Wednesday.

Police barricades remained up around Taksim Square and there was a heavy police presence around City Hall to enforce a four-day ban on protests.

Despite the ban, Galatasaray University students said they were boycotting lectures and several hundred began a protest march, an AFP correspondent said.

Students at Istanbul University, which on Tuesday revoked Imamoglu's degree, also began another day of protest.

The move is significant because Turkish law says presidential candidates must have a higher education qualification.

In both places, protesters carried banners with slogans such as "Shoulder to shoulder against fascism" and "Together against lawlessness".

CHP head and opposition leader Ozgur Ozel was expected to address protesters at City Hall again on Thursday at 1730 GMT, a party spokesman told AFP.

- Interrogations begin -

More than 80 people were rounded up in Wednesday's raids and investigators began quizzing them early on Thursday, local media said.

The mayor met with his lawyers, CHP said, but it was not immediately clear when he would be questioned.

Already named in a growing list of legal probes, Imamoglu -- who was resoundingly re-elected last year -- has been accused of "aiding and abetting a terrorist organisation" -- namely the banned Kurdish militant group PKK.

He is also under investigation for "bribery, extortion, corruption, aggravated fraud, and illegally obtaining personal data for profit as part of a criminal organisation" along with 99 other suspects.

Social media and internet access remained largely restricted in Istanbul on Thursday morning, according to online censorship monitor Free Web Turkey.

Interior Minister Ali Yerlikaya said 37 people had so far been detained for posting content online that was deemed "provocative" and more investigations were under way.

The authorities began blocking access to social networks early on Wednesday, with online services still noticeably slow a day later.

Despite the protest ban, thousands gathered outside City Hall late on Wednesday, chanting angry slogans including: "Erdogan, dictator!" and "Government, resign!"

- Backlash -

The move against Imamoglu was angrily denounced by the CHP as "a coup".

"Imamoglu's only crime was that he was taking the lead in opinion polls," party leader Ozel told the crowds at Wednesday night's protest, standing alongside Imamoglu's wife Dilek.

"His only crime was that he won the hearts of the people. His only crime was he would be the next president," he said.

Under the constitution, Erdogan -- who has been president for more than a decade -- cannot run again in the 2028 race, but he is seeking ways to change the constitution although he will need the opposition's support.

Hamish Kinnear, a senior analyst with Verisk Maplecroft risk consultancy, said the move against Imamoglu could end up harming those plans.

"It could upset the government's plan to push through constitutional change that would enable Erdogan to run for a third term," he said.

Erdogan already changed the constitution to introduce the presidential system after serving as premier for 11 years.

C.Diez--HdM