Istanbul Mayor Ekrem İmamoğlu has told police the allegations him against that sparked his arrest are "immoral and baseless", he said in a statement.
"The immoral and baseless accusations directed at me... are designed to undermine my standing and credibility," he told police, who quizzed him for five hours about allegations of "helping a terrorist organisation".
His arrest, early on Wednesday in connection with the "terror" probe and a second investigation alleging graft, has sparked mass protests in Turkey's worst unrest in more than a decade.
It has also hurt the Turkish lira and financial markets, with the benchmark BIST 100 index closing nearly 8% lower yesterday.
Watch: Police clash with protestors rallying over Istanbul mayor's detention
"This process has not only harmed Turkey's international reputation but has also shattered the public's sense of justice and trust in the economy," Mr İmamoğlu said.
"Those orchestrating this process will soon be held accountable before both divine and earthly courts."
Read more: In Turkey, mass protests give vent to long simmering anger
