Trump stepped back from his stance that Saudi Arabia's latest explanation for the death of the journalist inside the Saudi consulate in Istanbul was credible, but said he remained confident in the leadership of Crown Prince Mohammed bin Salman

US President Donald Trump has accused Saudi Arabia of lying about the killing of Jamal Khashoggi, his strongest comments to date on the affair as pressure was building Sunday on the administration to strike a tougher line.

In an interview with the Washington Post published late Saturday, Trump stepped back from his stance that Saudi Arabia's latest explanation for the death of the journalist inside their Istanbul consulate was credible, but said he remained confident in the leadership of Crown Prince Mohammed bin Salman.

"Obviously there's been deception and there's been lies," he said of the shifting accounts offered by Riyadh.

Saudi officials originally said Khashoggi, who entered the diplomatic mission on October 2, had left unharmed, before announcing Friday he was killed inside the building in what they described as an altercation.

"Their stories are all over the place," added Trump.

Saudi Arabia faced a growing chorus of incredulity Sunday, with world powers demanding answers. British and French officials denounced the latest Saudi explanation as insufficient. Canada's foreign minister, Chrystia Freeland, said the Saudi version lacked "consistency and credibility."

- Growing pressure -

Closer to home, pressure continued to grow on Trump to take a stronger stance against Saudi Arabia, the world's biggest oil exporter and a key regional power.

Several senior members of Trump's Republican Party said they believed Prince Mohammed, the kingdom's de facto ruler, was linked to the killing, and one called for a "collective" Western response if a link is proved.

But Trump stopped far short of calling for the prince to be replaced, emphasizing as he has before how important the US-Saudi relationship is to Washington's regional strategic goals.

He described the 33-year-old prince, widely known as MBS, as a "strong person; he has very good control."

"He's seen as a person who can keep things under check," added Trump. "I mean that in a positive way."

Trump added that he has yet to be shown any evidence by intelligence officials that would make him believe MBS had any direct role.

"Nobody has told me he's responsible. Nobody has told me he's not responsible. We haven't reached that point. I haven’t heard either way," the president said.

"There is a possibility he found out about it afterward. It could be something in the building went badly awry. It could be that's when he found out about it. He could have known they were bringing him back to Saudi Arabia."

- Republicans hit MBS -

Amid Trump's apparent equivocations, several key Republicans demanded a tougher stance.

Asked if he thought Prince Mohammed was behind the killing, a fellow Republican, Senator Bob Corker, told CNN: "Yes, I think he did it. Let's finish this investigation."

Corker, who chairs the Foreign Relations Committee, added that if the prince is implicated, "There should be a collective response."

"I think you're going to see the United States, United Kingdom, France, Germany working collectively with others if he did this to respond in an appropriate way."

Perhaps the strongest words came from Lindsay Graham, a strong Trump ally in the Senate who called for Prince Mohammed to "be removed."

"I would like to punish those involved. It's impossible to believe the crown prince wasn't involved. I don't mind military sales but I object to business with the current leadership," he said.

"This behavior is outside the norm to the point that the people involved need to be removed in my view. Saudi Arabia is a country and MBS is a person. I'm willing to separate the two," he continued, accusing the prince of acting in a "barbaric fashion."

Democrats have repeatedly lashed out at Trump's response as weak and indecisive, and they said his latest reaction fell short as well.

Barring an unlikely "confession" from Prince Mohammed, Democratic Congressman Adam Schiff said Sunday, "the president is going to accept the crown prince's denials like he's accepted Putin's denials and Kim Jong-Un's denials."

"We need to do a deep-dive probe in terms of Saudi Arabia," he said on ABC. "We have to see if financial motives are influencing the president."

Democratic Senator Dick Durbin meanwhile said: "We ought to expel, formally expel, the Saudi ambassador from the United States until there's a completion of a third party investigation into this kidnap, murder and God knows what followed that occurred in Istanbul."