Newly leaked CCTV footage has emerged that appears to show a man leaving the Saudi consulate in Istanbul wearing the clothes of the murdered journalist Jamal Khashoggi.

CNN aired the footage on Monday, citing a Turkish official who identified the man as Mustafa al-Madani, a "body double" and member of a 15-man Saudi team sent to Istanbul to target Khashoggi.

The footage appears to show the Saudi agent entering the consulate without a beard and wearing a blue and white checked shirt and dark blue trousers. Footage from later in the day appears to show him leaving the consulate dressed as Khashoggi, but wearing the same pair of trainers that he had arrived in.

Wearing glasses and a fake beard in an apparent attempt to further resemble the journalist, the agent is seen touring a number of landmarks in the Turkish city after leaving the consulate.

The apparent Saudi aim was for footage of the man to be picked up by CCTV and distributed, thereby bolstering claims made in the days after Khashoggi’s disappearance that he had left the consulate unscathed.

The killing of the Saudi journalist is a complicated murder that has been "monstrously planned", the spokesman for Turkey's ruling AK party said on Monday.

Khashoggi went missing on October 2 when he entered the kingdom's consulate in Istanbul. After weeks of denying knowledge of his fate, Saudi officials said the prominent journalist was killed in a "rogue operation".

Speaking to reporters in Ankara, Omer Celik also said claims of negotiations between Turkey and Saudi Arabia as part of the investigation into Khashoggi's killing were unethical, adding it was Turkey's responsibility to uncover the truth about the case.