In testimony before Congress Monday, a former White House official described a shadow foreign-policy apparatus that sought investigations into the president’s political foes — and former National Security Adviser John Bolton’s attempts to stymie their efforts, according to reports.

Fiona Hill, who served as the National Security Council’s senior official for Russia and Europe, made the revelations during a more-than nine-hour, closed-door testimony in Congress’ fast-moving impeachment inquiry into President Trump.

Hill said Bolton, her supervisor, was incensed upon learning that the president’s lawyer Rudy Giuliani, US ambassador to the European Union Gordon Sondland and acting White House chief of staff Mick Mulvaney had circumvented foreign policy officials and were secretly pressuring Ukraine into investigating the son of political rival Joe Biden.

Bolton was so perturbed that he ordered Fiona Hill to keep tabs on their meetings and disclose the findings to the chief lawyer for the National Security Council, three people with knowledge of Hill’s Monday’s testimony told The Times.

Hill testified that Bolton had once fumed Giuliani is like a “hand grenade who’s going to blow everybody up.”

Bolton learned they were going behind his back in a July 10 meeting with Sondland, former special envoy for Ukraine Kurt Volker, energy secretary Rick Perry and two Ukraine officials.

The meeting was supposed to address technical assistance to Ukraine’s national security council, and the Ukranians were keen on organizing a meeting between Trump and Ukraine President Volodymyr Zelensk, the report said.

Sondland got upset when Bolton wouldn’t commit to such a meeting, and blurted out that Mulvaney had already agreed a meeting would happen if Ukraine initiated investigations sought by the White House.

Bolton quickly concluded the meeting and directed Hill to keep an eye on Sondland and the Ukraine officials.

She overheard the group talk about the Ukrainian company that employed Hunter Biden, Burisman Holdings, as well as Rudy Giuliani, according to the report.

At that point, Hill went back to Bolton to report what she heard, which is when he instructed her report the findings to White House lawyer John Eisenberg.

The former national security adviser told Hill to relay a message to the lawyer: “I am not part of whatever drug deal Sondland and Mulvaney are cooking up,” two people familiar with the testimony told The Times.

Hill told Congress that she confronted Sondland, who told her Trump put him in charge of relations with Ukraine, despite the role being outside of his official purview, the report said.

Hill is the first former White House official to testify in the House impeachment probe.

With Post wires