Police have searched a forest in Istanbul where they believe his body may have been disposed of.
In a sign of growing pressure on Saudi Arabia, Turkey said it will announce details of its investigation into the killing of journalist Jamal Khashoggi on Tuesday and U.S. congressional leaders said the Gulf kingdom in particular its crown prince should face severe consequences for the death of the writer in the Saudi consulate in Istanbul.
Saudi Arabia, the president said, "has been a great ally in the Middle East".
However, he made clear he believed the Crown Prince Mohammed directed the murder.
Canada is among the latest countries to question Riyadh's version of events. The Saudi statements on Saturday did not address what happened to the body.More news: Post publishes possibly last image of missing Saudi reporter
"Saudi Arabia's changing stories on #KhashoggiMurder is getting old".
The kingdom has described assertions in Turkish media leaks, based on purported audio recordings that Khashoggi was tortured, killed and dismembered inside the consulate, as "baseless".
"We will ultimately make our judgement based on the credibility of the further explanation we receive about what happened and our confidence that such a shameful event can not and will not ever be repeated", it added.
Numan Kurtulmus, of the ruling Justice and Development Party, also said on Saturday that Turkey would share its evidence with the world and that a "conclusive result" of the investigation is close.
French Foreign Minister Jean-Yves Le Drian said many questions remained unanswered while German Chancellor Angela Merkel urged transparency, adding that "available reports on what happened in the Istanbul consulate are insufficient".
Trump tweeted that the Saudi Crown Prince "told me that he has already started, and will rapidly expand, a full and complete investigation into this matter".More news: Meghan Markle Is Cutting Back Her Royal Tour Schedule
US President Donald Trump suggested sanctions against Saudi were a possibility but said that halting arms deals would "hurt us more than it would hurt them". It was a good first step. "But I want to get to the answer".
His disappearance and presumed death has caused an worldwide outcry and strained relations between Saudi Arabia and the West.
The front pages of Saudi newspapers on Sunday were branded with headlines of support for the kingdom's government.
Offering condolences to Khashoggi's family, fiancee and friends, the foreign ministers said they "take note of the Saudi statement which gives their preliminary findings". Saudi Arabia is a country and MBS is a person.
Turkish police meanwhile are searching a forest on the outskirts of Istanbul and a city near the Sea of Marmara for Mr Khashoggi's remains, two senior Turkish officials told on Thursday. All of the identified individuals have since left Turkey.
Members of the suspected hit squad reportedly came to Britain during the prince's state visit.More news: Khashoggi killing: Saudi minister admits that his country is in crisis