President Donald Trump again escalated his war on Fox News, criticizing the anchor Chris Wallace's coverage of the Ukraine scandal that has led to an impeachment inquiry.

Trump tweeted on Sunday: "Somebody please explain to Chris Wallace of Fox, who will never be his father (and my friend), Mike Wallace" — a CBS interviewer who died in 2012 — "that the Phone Conversation I had with the President of Ukraine was a congenial & good one."

Fox News, long Trump's favorite network, has in recent months become a source of anger for him.

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President Donald Trump escalated his war on Fox News again, slamming the anchor Chris Wallace for his coverage of the Ukraine scandal and comparing Wallace unfavorably to his father, who died in 2012.

Trump tweeted on Sunday: "Somebody please explain to Chris Wallace of Fox, who will never be his father (and my friend), Mike Wallace, that the Phone Conversation I had with the President of Ukraine was a congenial & good one.

"It was only Schiff's made up version of that conversation that was bad!" he added, referring to Rep. Adam Schiff, the Democratic chairman of the House Intelligence Committee.

Trump has rejected that there was any wrongdoing during his July call with Ukrainian President Volodymyr Zelensky, which was the basis of an explosive whistleblower complaint that last month prompted Democrats to launch an impeachment inquiry into Trump.

Read more: As the impeachment probe intensifies, 40% of Americans say they think Mike Pence would make a better president than Trump

The White House's notes of the call showed that Trump, shortly after saying the US does "a lot for Ukraine," asked Zelensky to investigate the dealings of Joe Biden, the former US vice president who's now Trump's election rival, in Ukraine while Biden's son was on the board of a Ukrainian gas company. There is no evidence of wrongdoing by the Bidens.

Schiff, who's leading the inquiry stemming from the whistleblower complaint, has described Trump's call with Zelensky as a "classic Mafia-like shakedown." Trump has repeatedly accused Schiff of treason.

Mike Wallace, who died in 2012 at age 93, was a longtime CBS journalist who interviewed Trump when he was still a businessman for "60 Minutes."

Following his father's death, Chris Wallace described him as "the best reporter I have ever known."

Mike Wallace interviewing Trump in 1985. YouTube/CBS News

"And while work often came first for him, over the last 20 years, he worked hard to make connections with his family," Chris Wallace said. "He became my best friend. And at the end, he was surrounded by children, grandchildren, and even great-grandchildren. I already miss him terribly."

Fox News, long the president's favorite network, has become the subject of much of his ire in recent months as controversies around him deepen and some polls have found a slump in support. He reportedly fears that the network is not loyal enough to him.

Read more: Trump is reportedly worried that Fox News is being taken over by liberals trying to undermine him, as his war on the network escalates

In August, Trump said the network had "changed" and was "a lot different than it used to be."

"There's something going on at Fox, I'll tell you right now," he said. "And I'm not happy with it."

That prompted one of its anchors, Bret Baier, to hit back.

The network remains the home of some of Trump's closest allies, including some who've worked as his informal advisers. It often defends even his most controversial policies.