The CIA has concluded that Saudi Arabia's crown prince ordered the killing of journalist Jamal Khashoggi, according to reports.

Mr Khashoggi - a prominent critic of the Saudi regime, including powerful crown prince and de facto leader Mohammed bin Salman (often referred to as MBS) - disappeared after entering the Saudi consulate in Istanbul on October 2nd.

After initial denials, the Saudi government ultimately acknowledged that the journalist was murdered at the consulate.

The whereabouts of Mr Khashoggi's body remains unknown.

The Saudi public prosecutor this week said there are now 21 people in custody over the murder – with 11 indicted and referred to trial.

Five of those accused of the killing could face the death penalty.

Saudi officials have repeatedly denied that the crown prince was involved in the murder, claiming instead that two other senior officials ordered the killing.

However, The Washington Post - the newspaper which published Mr Khashoggi's columns - reports that the CIA has 'high confidence' in its assessment that Mohammed bin Salman ordered the assassination. 

It's reported that the conclusion has been reached based on "multiple sources of intelligence".

Other US media outlets, including the New York Times and CNN, also reported on the apparent CIA assessment.

A Saudi embassy spokesperson told CNN: "The claims in this purported assessment are false.

"We have and continue to hear various theories without seeing the primary basis for these speculations."

Turkey has previously insisted the killing came from the highest levels of the Saudi government - but not from King Salman.