Turkey cannot remain silent over the disappearance of Saudi journalist Jamal Khashoggi, President Tayyip Erdoğan said.
He added: Turkey is investigating all aspects of the case.
Khashoggi entered the Saudi consulate in Istanbul on Oct. 2 to get documents for his forthcoming marriage. Saudi officials say he left shortly afterwards but Turkish officials and his fiancee, who was waiting outside, said he never came out.
Erdoğan told reporters on a flight back from Hungary that Turkey is worried about the Khashoggi's disappearance.
"We are investigating all aspects of the event. It is not possible for us to remain silent regarding such an occurrence, because it is not a common occurrence," he said.
He also questioned assertions by Saudi authorities that the consulate does not have footage of Khashoggi leaving the building as the mission's security cameras only provide live footage and do not record images.
"Is it possible for there to be no camera systems at the Saudi Arabia consulate, where the event took place?," Erdogan said.
Turkey and the United States reached a deal in May over Manbij after months of disagreement. Under the deal, the YPG terrorists would withdraw from Manbij and Turkish and U.S. forces would maintain security and stability around the town.
"There is a delay but (the deal) is not completely dead. U.S. Secretary of State Pompeo and Defense Secretary Mattis say they will take concrete steps," Erdogan said.
The NATO allies have been carrying out coordinated but independent patrols in the region as part of the deal.
On Tuesday, Turkish Defence Minister Hulusi Akar said that joint training of U.S. and Turkish soldiers for patrols in Manbij had begun.
Relations between Turkey and the United States were further strained over the past few months by the trial of U.S. evangelical pastor Andrew Brunson in Turkey on terrorism charges, which he denies.
Asked about Brunson's trial, Erdoğan said he was not in a position to interfere with the judiciary.
"Whatever the judiciary decides on, I have to abide by that decision. Those who are involved with this also need to abide by the judiciary's decision," Erdoğan said.
The next session in Brunson's trial will be held on Friday.