Turkish President Recep Tayyip Erdogan says officials from Riyadh's consulate in Istanbul and a team from Saudi Arabia planned the murder of dissident Saudi journalist Jamal Khashoggi days in advance.

There is "strong evidence" that the killing was planned, Erdogan says in a speech in Ankara.

Employees of the consulate scouted a nearby forest prior to the incident while a team from Saudi Arabia was flown in a day before Khashoggi's death, he added.

The death of Khashoggi inside the Saudi consulate on October 2 was described as "murder" for the first time by Saudi Foreign Minister Adel al-Jubeir on Sunday.

The kingdom admitted on Saturday - 18 days after the incident - that Khashoggi indeed died in the consulate but blamed the death on a fistfight and said more than a dozen people were being questioned.