Turkish authorities believe that Saudi journalist Jamal Khashoggi, who disappeared four days ago after entering Saudi Arabia's consulate in Istanbul, was killed inside the consulate, two Turkish sources said on Saturday.
"The initial assessment of the Turkish police is that Mr Khashoggi has been killed at the consulate of Saudi Arabia in Istanbul. We believe that the murder was premeditated and the body was subsequently moved out of the consulate," one of the two Turkish officials said.
The Turkish sources did not say how they believed the killing was carried out.
A Saudi source at the consulate denied that Khashoggi had been killed at the mission and said in a statement that the accusations were baseless.
The Saudi source said that a security team including Saudi investigators had arrived in Istanbul on Saturday to take part in the investigation into Khashoggi's disappearance.
Saudi Arabia's consul-general said earlier on Saturday that his country was helping search for Khashoggi, and dismissed talk of his possible abduction.
Khashoggi, who has lived in self-imposed exile in Washington for the past year fearing retribution for his criticism of Saudi policies, entered the consulate on Tuesday to secure documents for his forthcoming marriage, according to his fiancee, who waited outside. He has not been heard of since.
Since then, Turkish and Saudi officials have offered conflicting accounts of his disappearance, with Ankara saying there was no evidence that he had left the diplomatic mission and Riyadh saying he exited the premises the same day.
The United States is seeking more information, a State Department official said.
"We are not in a position to confirm these reports, but we are following them closely," the official said.
A Turkish security source said that a group of 15 Saudi nationals, including some officials, had arrived in Istanbul in two planes and entered the consulate on the same day Khashoggi was there, and later left the country.
The Turkish source said Turkish officials were trying to identify them. Turkey's Anadolu news agency also reported that the group of Saudis were briefly at the consulate.
On Saturday, Yasin Aktay, ruling AK Party adviser and a friend of Khashoggi, told Qatari broadcaster Al Jazeera: "We demand a convincing clarification from Saudi Arabia, and what the crown prince offered is not convincing."
He also said what happened to Khashoggi was a crime and those responsible for his disappearance must be tried.
