US President Donald Trump says he never ordered his White House counsel at the time, Donald McGahn, to fire Special Counsel Robert Mueller.
The alleged instruction was described in the report Mueller wrote about his investigation into Russian meddling in the 2016 US election and whether the Trump campaign colluded with Russia.
"As has been incorrectly reported by the Fake News Media, I never told then White House Counsel Don McGahn to fire Robert Mueller, even though I had the legal right to do so. If I wanted to fire Mueller, I didn't need McGahn to do it, I could have done it myself," Trump wrote on Twitter.
The Democratic chairman of the House judiciary panel has issued a subpoena for McGahn to testify and provide documents to the committee, but it is not clear whether the White House will comply. Trump has vowed to fight every subpoena from House Democrats probing his administration.
Mueller's 448-page, partially-redacted report, which was released last week, uncovered numerous links between the Trump campaign and the Russian government, and described how Trump tried to impede the investigation.
The report mentioned an incident in June 2017 when Trump called McGahn to say the White House counsel should direct Deputy Attorney General Rod Rosenstein, who was overseeing the special counsel's probe, to remove Mueller.
Trump also tried to get McGahn to dispute media reports that the president had attempted to fire Mueller, the report said.
The Mueller report built a case indicating Trump had committed obstruction of justice but stopped shirt of concluding the president had committed a crime, although it also did not exonerate Trump.
The report also concluded there was not enough evidence to establish the Trump campaign engaged in a criminal conspiracy with Moscow.
