Philippine Vice President Sara Duterte said on Saturday she would have President Ferdinand Marcos Jr assassinated if she herself were killed, prompting Marcos' office to vow "immediate proper action."

In a dramatic sign of a widening rift between the two most powerful political families in the Southeast Asian nation, Duterte told an early morning press conference that she had spoken to an assassin and instructed him to kill Marcos, his wife, and the speaker of the Philippine House if she were to be killed.

"I have talked to a person. I said, if I get killed, go kill BBM (Marcos), (first lady) Liza Araneta, and (Speaker) Martin Romualdez. No joke. No joke," Duterte said in the profanity-laden briefing. "I said, do not stop until you kill them and then he said yes."