Turkey's opposition has called on supporters to rally outside the parliament in Ankara on Wednesday in defiance of an official ban on gatherings on a symbolic day for the republic.

A month after the arrest of Istanbul's mayor, Ekrem Imamoglu – President Recep Tayyip Erdogan's biggest political rival – the president of Imamoglu's Republican People's Party (CHP) said he would speak outside parliament as the country marks National Sovereignty Day. 

Ozgur Ozel, who was recently named as the leader of the CHP, which was established by the founder of the Turkish Republic, Mustafa Kemal Atatürk. Ozel reiterated a call to stage the rally in a post on X late Tuesday despite a government ban on gatherings.

"April 23 cannot be banned. Our gathering in front of parliament and our march to Anitkabir (Atatürk's Tomb) cannot be stopped," he said.

"I invite all residents of Ankara, especially young people and students, and everyone who will be in Ankara tomorrow, to go to Parliament at 5:00 p.m., Turkish flags in hand. Sovereignty belongs to the nation."

Imamoglu also referenced the rally from his cell at Silivri prison in Istanbul, where he has been held on corruption charges since March 25.

"I will watch this march for national sovereignty from prison. I will be at your sides. I will be marching with you," Imamoglu said on X.

Imamoglu's arrest has triggered a wave of protests in Turkey's main cities, primarily driven by young people.