The transcript made clear the killing was premeditated, and suggests several phone calls were made to give briefings on the progress, the source told the US network

Turkish officials believe those calls were made to top officials in Riyadh, CNN reported.

Khashoggi, a Saudi contributor to The Washington Post, was killed shortly after entering the kingdom's consulate in Istanbul on 2 October.

The transcript of the gruesome recording includes descriptions of Khashoggi struggling against his murderers, CNN said, and references sounds of the dissident journalist's body "being dismembered by a saw".

The original transcript was prepared by Turkish intelligence services, and CNN said its source read a translation version and was briefed on the probe into the journalist's death.

On Sunday, Saudi Arabia's foreign minister meanwhile rejected demands to extradite suspects connected to the murder of Khashoggi as sought by Turkish President Recep Tayyip Erdogan.

"We do not extradite our citizens," Adel al-Jubeir told a news conference in Riyadh at the end of a summit of Gulf Cooperation Council states.

According to Turkey, a 15-member Saudi team was sent to Istanbul to kill Khashoggi.

Erdogan has said the order to kill Khashoggi came from the highest levels of the Saudi government, but has insisted it was not King Salman.

After initially denying the murder, Saudi Arabia has acknowledged Khashoggi was killed inside the consulate but blamed his death on a "rogue" operation.

Despite speculation that the powerful crown prince ordered the hit, including a report concluded by the CIA, the kingdom has strongly denied he was involved, and has in recent weeks detained 21 people over the murder.

The murder has damaged Riyadh's international reputation and Western countries including the US, France and Canada have placed sanctions on nearly 20 Saudi nationals.