Secretary of State Mike Pompeo was a participant in a July 25 phone call with President Donald Trump and Ukrainian President Volodomyr Zelensky, The Wall Street Journal reported on Monday.

The State Department has already faced scrutiny over the extent of its involvement in the call, in which Trump pressured Zelensky to investigate former Vice President Joe Biden and his son Hunter.

The call is central to a whistleblower complaint that sparked an impeachment inquiry into Trump.

Pompeo on Friday was subpoenaed for documents related to the inquiry.

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Secretary of State Mike Pompeo was one of the participants in a July 25 phone call between US President Donald Trump and Ukrainian President Volodymyr Zelensky, The Wall Street Journal reported Monday.

Pompeo's involvement in the call had not been reported previously. The revelation further ropes the State Department into a brewing controversy surrounding allegations that Trump made efforts to pressure a foreign government to interfere in the 2020 election.

In the July call, Trump urged Zelensky to investigate former Vice President Joe Biden and his son Hunter.

The phone call is now at the heart of a whistleblower complaint from a US intelligence official that's catalyzed an impeachment inquiry into Trump. As part of this effort, the House Foreign Affairs, Intelligence, and Oversight committees on Friday subpoenaed Pompeo for related documents and scheduled depositions with five current or former State Department officials.

Read more: Read the full declassified whistleblower complaint about a phone call between Trump and Ukraine's president

The whistleblower complaint said approximately a dozen White House officials listened in on the July 25 call and specifically named top State Department official Ulrich Brechbuhl as one of the people on the call, though the whistleblower said they did not know if anyone was in the room with Trump during the call.

Pompeo has already faced questions about the extent of the department's involvement in facilitating contacts between Trump's personal lawyer Rudy Giuliani and an aide to Zelensky, Andriy Yermak. The whistleblower complaint said that the meeting was a "direct follow-up" to Trump's call with Zelensky about the "cases" they had discussed.

Giuliani, who has disputed the contents of the complaint and referred to it as "crap," last week said the State Department urged him to make contact with and meet Yermak in Madrid in early August. And on Sunday, Giuliani said Pompeo was aware of his efforts to pressure Ukraine to look into the Bidens.

"I did not do this on my own. I did it at the request of the State Department, and I have all of the text messages to prove it. And I also have a thank you from them from doing a good job," Giuliani said in an appearance on CBS's "Face the Nation."

The State Department has acknowledged that Kurt Volker, the former US special representative to Ukraine, put Giuliani and Yermak in touch. But a spokesperson told The Journal that Giuliani is "a private citizen and acts in a personal capacity as a lawyer for President Trump," adding that he "does not speak on behalf of the US Government."

Volker resigned on Friday, becoming the first official to step down in the wake of the launch of the impeachment inquiry and the release of the whistleblower complaint. He's among the five current and former State Department officials with scheduled hearings linked to the inquiry.

Giuliani has been involved in outreach to Ukraine for months and has said the State Department got in touch with him about it in July. But he told "Face the Nation" on Sunday that he didn't know of Pompeo's knowledge of his outreach until last week.

"When I spoke to the secretary last week, I said, 'Are you aware of this?' and he said, 'Yes, I know about this,'" Giuliani said, going on to suggest that the department wants to distance itself from his efforts with Ukraine.

"The State Department is running away from me," he said.

The State Department did not immediately respond to a request for comment.