Washington: The United States has identified some Saudi officials responsible for the killing of journalist Jamal Khashoggi and is taking action, including revoking visas and exploring sanctions, US Secretary of State Mike Pompeo says.

"These penalties will not be the last word on the matter from the United States," Pompeo told reporters on Tuesday.

"We're making very clear that the United States does not tolerate this kind of ruthless action to silence Mr. Khashoggi, a journalist, through violence."

Khashoggi's death in the Saudi consulate in Istanbul on October 2 has caused global outrage and strained relations between Riyadh and Washington. Khashoggi, a critic of Saudi Crown Prince Mohammed bin Salman, was a US resident and columnist for The Washington Post.

Earlier, US President Donald Trump said the Saudi authorities have staged the "worst cover-up ever" in the killing of prominent journalist Jamal Khashoggi this month.

Asked by a reporter in the White House Oval Office how the Khashoggi killing could have happened, Trump said: "They had a very bad original concept. It was carried out poorly, and the cover-up was one of the worst in the history of cover-ups."

AP