The Istanbul prosecutor's office has prepared a request for the extradition from Saudi Arabia of 18 suspects in the killing of Saudi journalist Jamal Khashoggi, the Turkish Justice Ministry said in a statement on Friday.

Riyadh has said 18 people have been arrested and five senior government officials have been sacked as part of an investigation into the case. Turkish President Tayyip Erdogan has called on the Saudi government to return the suspects to Turkey to face trial.