Donald Trump has erupted over the ongoing impeachment inquiry in a series of false and misleading tweets in which he accused investigators of being “human scum”.

“Corrupt politician Adam Schiff’s lies are growing by the day,” the US president tweeted on Thursday morning.

“Keep fighting tough, Republicans, you are dealing with human scum who have taken Due Process and all of the Republican Party’s rights away from us during the most unfair hearings in American History.

“But we are winning big, and they will soon be on our turf.”

In fact there is no evidence Mr Schiff, the House intelligence committee chairman, has lied and the impeachment inquiry his committee is conducting does not deny the US president any rights granted to him by the Constitution.

Mr Trump’s outburst came ahead of testimony to Congress by Fiona Hill, a former National Security official who is expected to criticise Republican attempts to promote a discredited conspiracy theory that it was Ukraine, and not Russia, which interfered in the 2016 US presidential election.

It also came the day after Gordon Sondland, America’s EU ambassador and a prominent Trump donor, dealt a serious blow to the president’s battle against impeachment by appearing to implicate him directly in attempts to pressure Ukraine into investigating Joe Biden, his political rival.

Earlier, Mr Trump railed against his preferred conservative news channel, Fox News, for featuring a Democratic pundit, before revealing he had asked Apple chief Tim Cook to help build 5G network capabilities across the US.

“The Republican Party, and me, had a GREAT day yesterday with respect to the phony (sic) Impeachment Hoax, & yet, when I got home to the White House & checked out the news coverage on much of television, you would have no idea they were reporting on the same event. FAKE & CORRUPT NEWS!” Mr Trump later tweeted.

He next went after New York prosecutors, who have in recent weeks subpoenaed Mr Trump’s accounting firm to demand eight years of his personal and corporate tax returns, the New York Times reported.

“Bob Mueller, after spending two years and 45 million dollars, went over all of my financials, & my taxes, and found nothing. Now the Witch Hunt continues with local New York Democrat prosecutors going over every financial deal I have ever done,” he tweeted.

“This has never happened to a President before. What they are doing is not legal. But I’m clean, and when I release my financial statement (my decision) sometime prior to Election, it will only show one thing – that I am much richer than people even thought – And that is a good thing. Jobs, Jobs, Jobs!”

Gordon Sondland says Donald Trump 'directed' quid pro quo

There is no evidence Mr Mueller accessed Mr Trump’s tax returns, and the special counsel probe into Russian interference in the 2016 election actually cost the far smaller total of $32 million (£24.7m).

Pivoting back to impeachment, Mr Trump claimed a 25 July phone call with Ukrainian president Voldymyr Zelensky in which he asked the new leader to investigate the Biden family was “perfect”.

“I never in my wildest dreams thought my name would in any way be associated with the ugly word, Impeachment! The calls (Transcripts) were PERFECT, there was NOTHING said that was wrong. No pressure on Ukraine. Great corruption & dishonesty by Schiff on the other side!” Mr Trump said, though he provided no evidence to support him claims over Mr Schiff.

Mr Trump later added, ”Read the two Transcripts of Ukrainian calls!” in reference to the 25 July call and an earlier phone conversation he had with Mr Zelensky.

The president also sparked anger when he said on Thursday he would block any efforts to oust a Navy SEAL at the centre of a high-profile war crimes case.

Mr Trump last week cleared Edward Gallagher, who was accused of murdering a teenage Isis prisoner in Iraq and of killing civilians. He was found not guilty of the most serious charges, but was convicted of posing for a photo with an Isis victim.

“The Navy will NOT be taking away Warfighter and Navy Seal Eddie Gallagher’s Trident Pin,” Mr Trump tweeted in reference to the Navy SEALs insignia.

“This case was handled very badly from the beginning. Get back to business!”

Mr Trump concluded with an extraordinary attempt to cast doubt on the testimony of US diplomat David Holmes, who said he had overheard a phone conversation between Mr Sondland and Mr Trump in which the president asked the EU ambassador if Ukraine was going to “do the investigation?”.