0747 GMT December 17, 2018
The request was made after the Foreign Ministry summoned the Saudi ambassador for a second time over the disappearance of Washington Post contributor Jamal Khashoggi, NTV broadcaster said.
A Turkish diplomatic source confirmed the Saudi envoy was "invited" to the ministry on Sunday in Ankara and was met by Deputy Foreign Minister Sedat Onal.
"The ambassador was told that we expected full cooperation during the investigation," the source said.
The ambassador was first summoned to the Foreign Ministry on Wednesday.
Khashoggi, 59, went to the consulate to obtain official documents ahead of his marriage to his Turkish fiancée. Turkish police said he never left the building.
However, Riyadh insisted Khashoggi left the consulate. But Turkish authorities believe Khashoggi was deliberately killed inside the consulate, a view echoed by one of Erdogan's advisers, Yasin Aktay, who is also a friend of the Saudi journalist.
The consulate on Sunday rejected the claims that the journalist was killed there as "baseless" in a post on Twitter.
In his first comments over the disappearance, Turkish President Recep Tayyip Erdogan on Sunday said he was awaiting the results of an investigation.
"We hope to have results very quickly," Erdogan said. "I am waiting, with high hopes."
Khashoggi had been critical of some of Saudi Crown Prince Mohammed bin Salman's policies and Riyadh's intervention in the war in Yemen.
AFP and Reuters contributed to this story.