WASHINGTON (AFP) - President Donald Trump sought on Wednesday (Nov 20) to distance himself from US envoy Gordon Sondland as he made an explosive appearance before an impeachment hearing, while also asserting that his testimony had exonerated him entirely.

"I don't know him very well. I have not spoken to him much," Trump told reporters at the White House, after the ambassador to the EU testified that he followed the president's orders in seeking a "quid pro quo" deal with Ukraine.

In an Oct 8 tweet, Trump had described his ambassador to the European Union as "a really good man and great American."

Trump went on to read from notes on Sondland's ongoing testimony, saying it demonstrated he did not pressure Ukrainian President Volodymyr Zelenskiy to investigate his political rival Joe Biden.

"It was a very short and abrupt conversation that he had with me," Trump said.

"'What do you want from Ukraine,'" the president quoted Sondland as asking him.

"Here is my response, that he gave. Just gave. Ready? You have the cameras rolling?

"Here is my answer: 'I want nothing. I want nothing. I want no quid pro quo. Tell Zelenskiy to do the right thing'," added the president, who reenacted the exchange several times to the reporters gathered on the South Lawn.

"Then he says: this is the final word from the President of the United States. I want nothing."

"I would say that means it's all over," Trump said.

Democrats are investigating Trump for allegedly abusing his office by pressing a foreign power - Ukraine - to interfere on his behalf in the 2020 US election.

In his testimony, Sondland said he was ordered by Trump to seek a "quid pro quo" deal in which Ukraine would probe Biden in exchange for a White House summit.

Sondland said he "never received a clear answer" on why the White House suspended security aid to Ukraine, which is battling Russian-backed separatists, but that he also "came to believe" it was tied to the investigations sought by Trump.