The mayor of Istanbul, Ekrem Imamoglu, a key opposition leader, has been arrested days before he was to be selected as a presidential candidate. Along with 100 others, he has been charged with corruption and aiding a terrorist group. The arrest comes as part of a major crackdown nationwide in recent months, targeting opposition politicians, municipalities, journalists and figures in the entertainment industry. It has triggered nationwide protests, with police using force to disperse crowds. The government has imposed four days of restrictions in Istanbul, banning public gatherings and limiting internet access. The opposition sees this as a politically motivated move to weaken Imamoglu’s challenge to president Recep Erdogan, whose party was recently defeated in elections in Istanbul and Ankara. The government denies interference, insisting on judicial independence. Imamoglu has faced other challenges, including the annulment of his university degree, which would disqualify him from running. The international community has condemned the arrest, warning of Turkey’s increasing authoritarianism.