US President Donald Trump vowed in a "60 Minutes" interview that the United States would get to the bottom of what happened to a missing Saudi journalist and that there would be "severe punishment" if he was found to have been murdered, CNN reported.

In an excerpt from the interview, released by CBS on Saturday morning, Trump said the case of Jamal Khashoggi was "being looked at very, very strongly" and that his administration "would be very upset and angry" if it turned out that the Saudi government had ordered his killing.

"As of this moment, they deny it and they deny it vehemently. Could it be them? Yes," he said.

Khashoggi, a columnist for the Washington Post, went into the Saudi consulate in Istanbul on October 2 to obtain paperwork that would allow him to marry his Turkish fiancée. He hasn't been seen in public since.