(Adds comment from Khashoggi fiancee; paragraphs 13,14)
RIYADH, Sept 26 (Reuters) - Saudi Arabia's crown prince said he bears responsibility for the killing of journalist Jamal Khashoggi last year by Saudi operatives "because it happened under my watch," according to a PBS documentary to be broadcast next week.
It is the first time that Mohammed bin Salman, the kingdom's de facto ruler, has publicly indicated personal accountability for the killing inside the Saudi consulate in Istanbul by operatives seen as close to him. The CIA and some Western governments have said they believe he ordered it, but Saudi officials say he had no role.
The death sparked a global uproar, tarnishing the crown prince's image and imperilling ambitious plans to diversify the economy of the world's top oil exporter and open up cloistered Saudi society. He has not since visited the United States or Europe.
"It happened under my watch. I get all the responsibility, because it happened under my watch," he told PBS' Martin Smith, according to a preview of a documentary, "The Crown Prince of Saudi Arabia," set to air on Oct. 1, ahead of the one-year anniversary of Khashoggi's death.
After initial denials, the official Saudi narrative blamed the murder on rogue operatives. The public prosecutor said the then-deputy intelligence chief ordered the repatriation of Khashoggi, a royal insider who became an outspoken critic, but the lead negotiator ordered him killed after discussions for his return failed.
Saud al-Qahtani, a former top royal adviser whom Reuters reported gave orders over Skype to the killers, briefed the hit team on Khashoggi's activities before the operation, the prosecutor said.
Asked how the killing could happen without him knowing about it, Smith quotes Prince Mohammed as saying: "We have 20 million people. We have 3 million government employees."
Smith asked whether the killers could have taken private government jets, to which the crown prince responded: "I have officials, ministers to follow things, and they're responsible. They have the authority to do that." Smith describes the December exchange, which apparently took place off camera, in the preview of the documentary.
A senior U.S. administration official told Reuters in June the Trump administration was pressing Riyadh for "tangible progress" toward holding to account those behind the killing ahead.
Eleven Saudi suspects have been put on trial in secretive proceedings but only a few hearings have been held. A U.N. report has called for Prince Mohammed and other senior Saudi officials to be investigated.
Khashoggi, a Washington Post columnist, was last seen at the Saudi consulate in Istanbul on Oct. 2, where he was to receive papers ahead of his wedding. His body was reportedly dismembered and removed from the building, and his remains have not been found.
At an investment conference in Riyadh a few weeks after the murder, the crown prince called it a "heinous crime" and a "painful incident", promising to bring to justice those responsible.
Khashoggi's fiancée, Hatice Cengiz, told an event on the sidelines of a U.N. annual gathering of world leaders that she had two questions for the crown prince: who gave the order for Khashoggi to be killed and why?
"By confessing this, he's also distancing himself from the killing of Jamal," Cengiz said, speaking through an interpreter.
"He's saying that it happened under his watch but he means he is not involved in this crime. His statement is a pure political manoeuvre." (Reporting by Stephen Kalin in Riyadh and Michelle Nichols at the United Nations; Editing by Gerry Doyle, William Maclean)
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