US President Donald Trump said Saturday he was "not satisfied" with Saudi Arabia's explanation of how Washington Post columnist Jamal Khashoggi met his death in the Saudi consulate in Istanbul.

"I'm not satisfied until we find the answer," he told reporters, adding that he was still considering sanctions and would speak to Crown Prince Mohammed bin Salman, effectively the kingdom's ruler, soon.

However, Trump said it was "possible" that the crown prince knew nothing about the killing, and that cancelling an arms deal "would hurt us far more than it would them."

His comments came as Canada, the European Union, and separately France, called for a transparent investigation into Khashoggi's death, while Germany indicated it may suspend arms sales to Saudi Arabia.

Saudi Arabia's claim that 60-year-old Khashoggi died following a "fist fight" at its consulate on October 2 has been met with widespread scepticism.

Prior to its admission Saturday, Riyadh had denied Saudi officials had any knowledge of what had happened to the dissident journalist, saying he had left the consulate after picking up papers for his forthcoming marriage.

Turkish officials have told media that Khashoggi was murdered and dismembered, and that they have audio and video tapes to back up their claims.

Trump, who has embraced an alliance with the crown prince, said it was a "concern" that Saudi Arabia had not revealed the whereabouts of Khashoggi's body, for which Turkish authorities are still searching.

Turkish officials earlier Saturday vowed to reveal the truth of what took place.

Canada's Foreign Affairs Minister Chrystia Freeland said Saudi Arabia's explanations lacked "consistency and credibility," and said those responsible for his death "must be held to account."

Saudi Arabia expelled the Canadian ambassador in August and halted all new investment and trade transactions with Canada, after Freeland tweeted her concern at the detention of Saudi human rights activists.

EU foreign policy chief Federica Mogherini said the "emerging circumstances" of Khashoggi's death were "deeply troubling" and called for a "continued thorough, credible and transparent investigation."

French Foreign Minister Jean-Yves Le Drian also called for an "comprehensive investigation," adding: "The confirmation of the death of Mr Jamal Khashoggi is a first step towards determining the truth."

German Chancellor Angela Merkel and her Foreign Minister Heiko Maas meanwhile issued a joint statement demanding "transparency" from Saudi Arabia and saying that explanations so far were "insufficient."

Maas told German broadcaster ARD that weapons sales should be suspended to Saudi Arabia while questions remained about Khashoggi's death and said he would not take part in any events there.

Saudi Arabia is Germany's second biggest customer in terms of arms.

Australia has joined a growing list of countries and businesses boycotting an investment conference in Saudi Arabia this month, according to the news agency AAP, with Prime Minister Scott Morrison on Sunday calling on Riyadh to "co-operate fully with Turkish authorities."