* Seeks arrest of al-Qahtani and al-Asiri
* Move comes after US senators received CIA briefing
* Erdogan has sought to keep case in spotlight
* UN rights chief calls for investigation
Istanbul's chief prosecutor has filed warrants for the arrest of a top aide to Saudi Arabia's de facto ruler and the deputy head of its foreign intelligence on suspicion of planning the killing of Jamal Khashoggi, two Turkish officials said on Wednesday.
The prosecutor's office has concluded there is "strong suspicion" that Saud al-Qahtani and General Ahmed al-Asiri, both removed from their positions in October, were among the planners of Khashoggi's Oct. 2 killing at the Saudi consulate in Istanbul, the officials said.
The move comes a day after senior US senators said they were more certain than ever that Saudi Crown Prince Mohammed bin Salman was responsible for the killing, citing a CIA briefing. The United Nations human rights chief on Wednesday called for an international investigation.
Turkish President Tayyip Erdogan has pushed to keep international attention on the murder - the order for which he says came from the highest levels of the Saudi government - even as US President Donald Trump has said Washington should not take action that would undermine its relationship with the kingdom.
"The prosecution's move to issue arrest warrants for Asiri and Qahtani reflects the view that the Saudi authorities won't take formal action against those individuals," one of the Turkish officials said.
"The international community seems to doubt Saudi Arabia's commitment to prosecute this heinous crime. By extraditing all suspects to Turkey, where Jamal Khashoggi was killed and dismembered, the Saudi authorities could address those concerns," the official said.
Erdogan has said the order for Khashoggi's killing probably did not come from King Salman, putting the spotlight instead on Salman's heir and de facto ruler Prince Mohammed.
Saudi Arabia has said the prince had no prior knowledge of the murder. After offering numerous contradictory explanations, Riyadh later said Khashoggi had been killed and his body dismembered when negotiations to persuade him to return to Saudi Arabia failed.
Making some of their strongest accusations so far, both Republicans and Democrats said they want to pass legislation to send a message to Saudi Arabia that the United States condemns the death of Khashoggi, a Washington Post columnist.
"You have to be willfully blind not to come to the conclusion that this was orchestrated and organised by people under the command of MbS," Republican Senator Lindsey Graham told reporters after the meeting with Central Intelligence Agency Director Gina Haspel, referring to the crown prince by his initials.
Graham, who has become one of the president's most vocal allies, said there may not be a "smoking gun," but that there was a "smoking saw," a reference to a bone saw that investigators said was used to cut up Khashoggi's body.
Trump and some of his fellow Republicans have argued that Washington should not take action that would risk its relationship with Riyadh, which is viewed as an important counterweight to Iran in the Middle East.
Erdogan has said that solving the Khashoggi killing would also be in the interest of the Saudi monarchy.
The United States last month imposed economic sanctions on 17 Saudi officials for their role in the killing. Among those sanctioned were Qahtani, who was formerly a top aide to the crown prince.
Qahtani had tried to lure Khashoggi back to Saudi Arabia after he moved to Washington a year ago fearing reprisals for his views, according to people close to the journalist and the government.
But Asiri, the former deputy head of foreign intelligence, was not on the sanctions list. Saudi Arabia's public prosecutor has said Asiri was the one who ordered the operation to repatriate - but not kill - Khashoggi.