Trump says 'full report' on Khashoggi's murder due in days

"Recent reports indicating that the US government has made a final conclusion are inaccurate," State Department spokeswoman Heather Nauert said in a statement.

"There remain numerous unanswered questions with respect to the murder of Mr. Khashoggi. The State Department will continue to seek all relevant facts," she said. 

"In the meantime, we will continue to consult Congress, and work with other nations to hold accountable those involved in the killing of Jamal Khashoggi". 

She added that Washington had already taken "decisive measures" against individuals, including visa and sanctions actions.

But most observers say the sanctions are weak and do not hold those responsible for Khashoggi's death to account. 

"We will continue to explore additional measures to hold those accountable who planned, led and were connected to the murder. And, we will do that while maintaining the important strategic relationship between the United States and Saudi Arabia," she added, a nod to the close relationship Washington has forged with the ultra-conservative kingdom. 

The Washington Post, which broke the CIA story, said the intelligence agency found that 15 Saudi agents flew on government aircraft to Istanbul and assassinated Khashoggi in the Saudi consulate.

Khashoggi, a Post columnist, had gone to the consulate to obtain documents necessary to marry his Turkish fiancee.

Saudi Arabia - which quickly dismissed the reported CIA findings - has repeatedly changed its official narrative of the 2 October murder, first denying any knowledge of Khashoggi's whereabouts and later saying he was killed when an argument degenerated into a fistfight.

In the latest version presented by the Saudi prosecutor on Thursday, a 15-member squad was formed to bring Khashoggi back from Istanbul "by means of persuasion" - but instead ended up killing the journalist and dismembering his body in a "rogue" operation.

The killing of Khashoggi has triggered an international uproar and brought the Trump administration's relationship with Riyadh, which has sought to end discussion of the murder and rejected calls for an international investigation, under renewed scrutiny. 

But ahead of a briefing by his secretary of state and CIA director, Trump demured when asked about possible retaliation against Riyadh.

"They have been a truly spectacular ally in terms of jobs and economic development," Trump told reporters. 

Trump's first foreign trip as US president was to Saudi Arabia, and Riyadh remains the lynchpin of his region strategy to contain Iran.