Saudi Arabia rejected threats to punish it over the disappearance of journalist Jamal Khashoggi in Istanbul, saying the kingdom will retaliate against any sanctions with tougher measures, the official state news agency said Sunday.

The comments came after U.S. President Donald Trump threatened "severe punishment" for Riyadh if it turns out Khashoggi, a prominent critic of Saudi authorities and a legal resident of the United States, was killed in the Saudi Arabian Consulate in Istanbul.

"The kingdom affirms its total rejection of any threats and attempts to undermine it, whether by threatening to impose economic sanctions, using political pressures, or repeating false accusations . . . " the official Saudi Press Agency quoted an unnamed government source as saying.