He said 18 Saudis had been arrested and two top aides of Crown Prince Mohammed had been sacked, together with three other intelligence agents.
He added: "Why did those 15 men come here?"
The UK Foreign Office described it as "a awful act" and said the people behind the killing "must be held to account". "All of this needs to be explained in all its details", Erdogan said. Our condolences go out to them.
The images taken from CCTV footage shows that Khashoggi was wearing what appears to be a black jacket, a light grey shirt and grey pants when he entered the consulate. The images, taken from security camera video, show the writer being searched before continuing toward the building. King Salman has ordered Crown Prince Mohammed bin Salman to lead the charge of revamping the country's intelligence services.
"The market started to price in a fundamentally different relationship between Saudi Arabia and the USA", said Jaap Meijer, head of equity research, at Arqaam Capital. "That is unacceptable to the government".
RIYADH, Saudi Arabia-The latest twist in an official narrative over how a government critic died inside Saudi Arabia's Istanbul consulate has eroded the government's credibility domestically and deepened concerns about expressing views in public.
Bob Corker, chairman of the Senate Foreign Relations Committee, said Saturday on CNN's "State of the Union" that he believed Prince Mohammed, the heir-apparent of the world's largest oil exporter, was behind the killing.
"Obviously if he's gone forth and murdered this journalist, he's now crossed the line, and there has to be a punishment and a price to pay for that".
Saudi Arabia said information provided by Turkey helped the Kingdom reveal the truth about Khashoggi's murder.
"We have an important relationship with Saudi, focused on combating terrorist financing and focused on our common interests of stopping Iran's spread of both terrorism and other issues", Mnuchin said Sunday, as The New York Times reported.
U.S. Treasury Secretary Stephen Mnuchin said on Sunday that Saudi Arabia's admission that the Washington Post columnist had been killed in a fistfight was a "good first step but not enough", though he added it was premature to discuss any sanctions against Riyadh.
Mr Gardiner acknowledged there were a "lot of jobs" in the United Kingdom linked to the defence trade but said "this is about who we are as a country".
I would like to comment on the current situation regarding the journalist Jamal Khashoggi's disappearance. Saudi Arabia ranked sixth a year ago with approved sales of 254 million euros ($292 million), mostly reflecting deliveries of patrol boats, according to a government report published in June. Speaking late Saturday after a campaign rally in Nevada, Trump said he needs to learn more about the killing and will be working with Congress on the USA response.
Khashoggi also criticized Prince Mohammed's lack of "proper advisers".