The US President has termed CIA's conclusion in the Jamal Khashoggi murder as "not definitive", prompting a Senate Committee to ask Donald Trump for a fresh probe to determine within four months whether Saudi Crown Prince Mohammed bin Salman had any role in the killing.

Republican and Democratic leaders of the US Senate Foreign Relations Committee on Tuesday sent a letter demanding a second investigation after Trump earlier in the day said the CIA had not reached a "definitive" conclusion.

Trump defended US ties with Saudi Arabia saying it was clear who ordered the murder, despite press reports saying the agency has determined that Salman ordered the hit as international condemnation of the brutal killing continued.

Republican Senator Bob Corker and Democrat Bob Menendez issued a statement asking for a second probe by the Trump administration after the US President stated earlier in the day that the CIA had not made a "100%" determination on the killing.

Trump acknowledged that the crown prince "could very well" have known about Khashoggi's brutal murder, adding: "Maybe he did and maybe he didn't!"

Khashoggi was killed on October 2 inside the Saudi consulate in Istanbul, Turkey.

Following the President's comments, the Senate Committee called on Trump to focus on a fresh probe specifically on the crown prince so as to "determine whether a foreign person is responsible for an extrajudicial killing, torture or other gross violation" of human rights. 

The senate's request, issued under the Global Magnitsky Human Rights Accountability Act, requires a response within 120 days.

Saudi Arabia has blamed Khashoggi's death on rogue agents but denied claims that the crown prince had knowledge of the operation. The US media have reported that the CIA believes Salman ordered the murder.

In an interview on Sunday, Trump told Fox News that he had refused to listen to a recording of Khashoggi's murder provided by Turkey and called it "a suffering tape".