UN Secretary-General Ban Ki-moon on Wednesday expressed deep concern about the ongoing wave of arrests in Turkey following the attempted coup.

UN Secretary-General Ban Ki-moon on Wednesday expressed deep concern about the ongoing wave of arrests in Turkey following the attempted coup.

Ban told Foreign Minister Mevlut Cavusoglu during a telephone conversation that "credible evidence" must be presented swiftly so that the detainees' legal status can be determined by a court of law.

More than 15,000 people including military officials were detained during the massive sweep that followed the July 15 failed coup and at least 8,000 remain in custody.

On Wednesday, Turkish authorities issued arrest warrants for dozens of journalists including 47 former staff of the Zaman daily, one of the country's biggest newspapers.

In his conversation with the foreign minister, Ban "referred to worrying reports of mistreatment and abuse of some of those who are still in custody and their detention conditions, and underscored his deep concern about the scope of continuing widespread arrests, detentions and suspensions," said UN spokesman Farhan Haq.

"Credible evidence on those under investigation has to be presented swiftly to the judicial system so that legal determination could be made before the court of law," he added.

The UN chief said that while he recognized the "extraordinary circumstances prevailing in the country following the coup attempt", he expected Turkey to uphold fundamental rights and to adhere to its international obligations.

Ban has spoken out repeatedly on the need for Turkey to respect freedom of speech and assembly and to uphold due process.

Turkey's Prime Minister Binali Yildirim warned the crackdown and purge unleashed after the coup was not over.

The UN chief "trusts that the government and people of Turkey will transform this moment of uncertainty into a moment of unity, preserving Turkey's democracy," the spokesman added.