So far it still remains unclear how Trump would "punish" the kingdom economically over the journalist's disappearance, but major figures in the US Congress, such as Florida Senator Marco Rubio, have suggested halting arms sales to Saudi Arabia.
Turkish forensics and police officers arrive to the Saudi Arabia's consulate in Istanbul on October 15, 2018, to search the premises in the investigation over missing Saudi journalist Jamal Khashoggi.
The Turkish government believes Khashoggi was killed and dismembered inside the consulate, and his body removed in suitcases or boxes.
"The king firmly denied any knowledge of it", Trump told reporters after speaking with King Salman.
Saudi Arabia is considering an admission that journalist Jamal Khashoggi died during an interrogation that went wrong, USA media reported on Monday.
But Sen. Marco Rubio (R-Fla.) said Mnuchin should not attend the economic summit because the U.S. should not continue "business as usual" with Saudi Arabia in the wake of Khashoggi's disappearance.
The Saudi stock exchange opened about 2 per cent higher, after a plunge of at least 7 per cent the day before following President Donald Trump's warning that the oil-rich kingdom deserved "severe punishment" if it is proven to have been responsible for Khashoggi's disappearance.
He adds: "We're going to try getting to the bottom of it very soon, but his was a flat denial". The Khashoggi case itself also threatens to derail Crown Prince Mohammed bin Salman's worldwide effort to rebrand the kingdom.
Turkish officials have said they have audio and video that proves Khashoggi was murdered inside the Saudi Consulate in Istanbul earlier this month.
The newspaper also alleged Saudi officials tried to delete the recordings first by incorrectly guessing Mr Khashoggi's PIN on the watch, then later using the journalist's finger.
In a joint statement, the nations called for a "complete and detailed response" from Saudi Arabia.
United States politicians have backed the call for tough punitive action against the Saudis, while Germany, France and Britain have jointly called for a "credible investigation" into his disappearance.
Ford Motor Co Chairman Bill Ford also pulled out, as well as media organizations like CNN and Bloomberg which once served as sponsors of the conference. "So I'd be careful to wait until we see what the facts are".
Khashoggi was a critic of the regime in effect led by the Bin Salman since his father appointed him crown prince in June 2017. He said that Saudi Arabia had made investments in hotels, manufacturing and real estate in the USA and that cutting these would "hurt the U.S. economy significantly".
Saudi Arabia hit back hard, warning that the kingdom would respond to any steps taken against itwith "greater action".