A man mourns by a makeshifts memorial made of candles and posters picturing Saudi journalist Jamal Khashoggi during a gathering outside the Saudi Arabia consulate in Istanbul, on October 25, 2018. (AFP photo)

ISTANBUL, Oct. 26 (Xinhua) -- Turkish prosecutors on Friday demanded the extradition of 18 Saudi suspects who were arrested in Saudi Arabia a week ago over their alleged roles in the killing of journalist Jamal Khashoggi, local media reported.

The broadcaster NTV said the Istanbul Public Prosecutor's Office submitted the extradition request to Turkey's justice ministry to be delivered to Saudi officials.

Turkish President Recep Tayyip Erdogan earlier on the day said Saudi Arabia's chief prosecutor would visit Istanbul on Sunday as part of the investigation of the case.

The Saudi journalist has not been seen since he entered the kingdom's consulate in Istanbul on Oct. 2 to obtain documents related to his upcoming remarriage.

Riyadh has confirmed Khashoggi's death inside its consulate while Turkish police have been searching for clues about the whereabouts of his body across the city.