Donald Trump has ignored a rebuke from his attorney general about  commenting on ongoing cases, taking to social media to insist he has “the legal right” to do so.

The US President has criticised the judge, jury and prosecutors in the criminal case of his longtime adviser Roger Stone.

Mr Trump’s comments have prompted Attorney General William Barr, his top law enforcement official, to warn about the potential risk to the independence of the US legal system.

The latest episode has spurred new demands for investigation from the Democrats who unsuccessfully tried to remove the Republican president from office.

It was the latest in a string of aggressive actions by Mr Trump since the Republican-controlled Senate acquitted him of impeachment charges last week.

Mr Trump has transferred or fired government officials who testified about his efforts to pressure Ukraine to investigate a potential political rival in November’s presidential election.

He also dropped his nomination of former US Attorney Jessie Liu, who oversaw the Stone case, for another government post in the Treasury Department.

Sources close to the President said Mr Trump has a greater sense of freedom following his Senate acquittal.

“You have to remember, he’s not ‘of’ government. He gets frustrated when people tell him something can’t get done. He’s like: ‘Just get it done,'” said one administration official who spoke on condition of anonymity.

Mr Barr has privately told Mr Trump for “some time” that his public statements were making it hard for him to run the Justice Department effectively, according to a source familiar with the matter.

He went public on Thursday, telling ABC News that Mr Trump’s attacks made it “impossible” for him to do his job. “It’s time to stop the tweeting,” he said.

Mr Trump “has never asked me to do anything in a criminal case,” Mr Barr added.

The president responded on Friday morning. “This doesn’t mean that I do not have, as President, the legal right to do so, I do, but I have so far chosen not to!” he wrote on Twitter.

“The President has never asked me to do anything in a criminal case.” A.G. Barr This doesn’t mean that I do not have, as President, the legal right to do so, I do, but I have so far chosen not to!

— Donald J. Trump (@realDonaldTrump) February 14, 2020

Administration officials said Mr Barr did not clear his remarks with Mr Trump. They said Mr Trump shrugged them off when told about them by aides.

Mr Trump’s insistence that he has the right to interfere in criminal cases runs counter to the practice of previous US presidents, who have generally kept an arms-length distance from the Justice Department since the Watergate scandal of the 1970s that led then-President Richard Nixon to resign from office.

“Trump goes farther than Nixon, though. He’s proud to openly corrupt the justice system and use it to target his enemies and protect his friends,” Democratic Senator Ron Wyden said in a prepared statement.

Mr Trump’s running commentary on the Stone case calls into question whether Mr Barr can oversee US law enforcement in an independent manner, said Bruce Green, a former federal prosecutor who now teaches at Fordham School of Law.

“Given the sequence of events, it’s doubtful that Barr’s effort to distance himself from the president’s tweets will be enough of a cure,” Mr Green told Reuters.

Mr Barr has been an outspoken defender of the president and has aggressively sought to implement his agenda, frequently drawing charges from Democrats and former Justice Department officials that he is politicising the rule of law.

– with agencies