Donald Trump says he is “demanding” answers from Saudi Arabia over missing journalist Jamal Khashoggi.
The US president, a key ally of the oil-rich Gulf state, said he had spoken with Saudi representatives about the “bad situation” with the journalist but did not disclose details of the conversations.
Mr Khashoggi has not been seen since he walked into the Saudi consulate in Istanbul last week and never came out.
Turkish officials believe the critic of the Saudi regime was killed in the consulate, and have published images of an alleged “assassination squad” and movements around the building at the time of Mr Khashoggi’s disappearance.
Saudi Arabia asserts the allegations are “baseless”.
Mr Trump also says he has reached out to Mr Khashoggi’s fiance, Hatice Cengiz, and invited her to the Oval Office.
He told reporters that “nobody knows what happened yet”, and expressed a hope that the journalist may still be alive.
“It’s a very serious situation for us and this White House,” he said.
The president had been criticised for his mild response to the disappearance of the journalist, with members of Congress imploring his administration try to get to the bottom of the disappearance.
Stakes are high in the relationship between the United States and Saudi Arabia, and Mr Trump is one of many Western leaders to stand by the kingdom’s young leader Mohammed bin Salman.
He has endorsed the crown prince despite rights organisations expressing serious concerns over the imprisonment and persecution of dissidents, and the ongoing Saudi bombing of Yemen.
I have great confidence in King Salman and the Crown Prince of Saudi Arabia, they know exactly what they are doing….
— Donald J. Trump (@realDonaldTrump) 6 November 2017
In an article for the Washington Post, Ms Cengiz pleaded with Mr Trump and his wife Melania to “help shed light” on the disappearance of her partner.
She also urged Saudi Arabia to release CCTV footage of when her fiance disappeared.
“Although this incident could potentially fuel a political crisis between the two nations, let us not lose sight of the human aspect of what happened,” she wrote.
“I don’t know how I can keep living if he was abducted or killed in Turkey.”
The 36-year-old student was waiting outside the consulate in Istanbul when Mr Khashoggi entered it a week ago, hoping to fix paperwork for their imminent marriage.