US HOUSE of Representatives Speaker Nancy Pelosi accused President Donald Trump of threatening national security amid growing calls for his impeachment for allegedly pressing Ukraine’s government to investigate a political rival.

Ms Pelosi was speaking after the president told the United States mission to the United Nations that the whistleblower who leaked details of a phone conversation with his Ukrainian counterpart Volodymyr Zelensky was guilty of espionage.

Mr Trump said: “I want to know who’s the person who gave the whistleblower the information because that’s close to a spy,” implying that revealing details of the call was an act of treason, which carries the death penalty.