ANKARA —  Turkish authorities expanded a ban on public demonstrations in Ankara and Izmir on Friday as protests over the detention of Istanbul Mayor Ekrem Imamoglu, a key rival of President Recep Tayyip Erdogan and a potential presidential contender, spread overnight.

The governor’s offices in Ankara and Izmir imposed a five-day demonstration ban on Friday. A similar ban has been in effect in Istanbul since Wednesday. Access to social media sites, including X, YouTube, Facebook and Instagram, remains restricted, according to the UK-based internet watchdog Netblocks.

Yet it remains unclear whether the ban will stop the protesters, as scores of people have already started to gather outside of Istanbul city hall for a third consecutive night, TV footage showed. The Istanbul governor’s office closed the main roads leading to the city hall.

Overnight Thursday, protests erupted in several provinces across Turkey, with hundreds gathering in Ankara, the capital, the Aegean port city of Izmir, the Mediterranean province of Adana, and Imamoglu’s hometown, Trabzon, on the Black Sea.