The outright rebuff by Foreign Minister Adel al-Jubeir on Saturday came a day after President Recep Tayyip Erdogan renewed his call for the 18 men to be extradited for trial in Turkey.
"The individuals are Saudi nationals. They're detained in Saudi Arabia, and the investigation is in Saudi Arabia, and they will be prosecuted in Saudi Arabia," Jubair told a regional security forum in Bahrain.
Saudi authorities say they have arrested the men following the international furor over Khashoggi's murder, which was reportedly carried out in the consulate by a team which flew to Istanbul.
Turkish Justice Minister Abdulhamit Gul said on Friday that Istanbul's chief prosecutor had formally written the request for their extradition.
"The Turkish authorities are determined and able to solve this case. We expect the extradition," he said in a statement, adding that the suspects would be tried on charges of premeditated murder and torture.
A senior Turkish official said “the reasoning behind the extradition request is that Jamal Khashoggi was murdered in Turkey by Saudi nationals who traveled to Turkey for this specific purpose.”
But the Saudi foreign minister said the kingdom would carry out investigations on its own.
"The issue, as I said, is being investigated. We will know the truth. We will hold those responsible accountable. And we will put in place mechanisms to ensure it doesn't happen again," Jubeir said.
Khashoggi, a supporter-turned-critic of Saudi Crown Prince Mohammed bin Salman, never left the Saudi mission in Istanbul after entering it on October 2.
In a belated ackhnowledgement, which followed repeated denials, Saudi Arabia finally admitted that Khashoggi had been killed when “discussions” at the consulate turned into “a brawl.”
However, Saudi Arabia's public said that the murder of Khashoggi, a US resident and Washington Post
contributor, was premeditated.
Riyadh’s admission of Khashoggi’s murder triggered international outcry. Erdogan has said 15 of the 18 men flew from Riyadh to Istanbul on the day Khashoggi disappeared, while the three others were already inside the consulate.
Several of those behind Khashoggi's murder were from bin Salman's personal security staff, reports have said.
Turkish investigators have said they are in possession of recordings that show Khashoggi was tortured before his death and his body dismembered with a bone saw by a Saudi hit squad.
On Friday, Erdogan urged Saudi Arabia to disclose the location of Khashoggi’s body and identify who ordered his killing.
A Turkish driver, who transported some of the members of the Saudi hit squad in Istanbul, said they appeared “cheerful” on their way from hotel to the airport.
“They asked me for a place to eat and I brought them to a doner restaurant. They were very cheerful. They smoked and drank alcohol in the car,” he said.