U.S. President Donald Trump visits West Virginia

Washington - US President Donald Trump said Thursday that if he wanted to fire special counsel Robert Mueller, who is investigating alleged Russian meddling in the 2016 US elections, he would have done it months back.

"If I wanted to fire Robert Mueller in December, as reported by the Failing New York Times, I would have fired him," Trump tweeted. "Just more Fake News from a biased newspaper," he wrote in a reference to a Tuesday report.

US media have speculated for months that Trump would like to fire Mueller, whose investigation has looked into alleged misdeeds by people in Trump's presidential campaign.

Mueller's special prosecution was enabled a year ago by Deputy Attorney General Rod Rosenstein after Trump sacked then FBI director James Comey, reportedly because Comey refused to pledge loyalty to the president.

Trump tweeted later Thursday that he agreed with the "historically cooperative, disciplined approach" that he said his administration had had with Mueller. He added that he had full confidence in Ty Cobb, his lawyer, and "have been fully advised throughout each phase of this process."

Mueller's investigation has so far seen former Trump's national security advisor Michael Flynn plead guilty to making false statements, won an indictment against campaign official Paul Manafort for money laundering, and overseen a case that led to a guilty plea by Rick Gates, another campaign official for conspiracy.

This week, FBI agents raided the offices of Trump's personal lawyer, Michael Cohen, reportedly while searching for documents related to alleged affairs the president had. The tip that led to the raid allegedly came from the Mueller investigation.

On Wednesday, a Trump spokeswoman said the president believes he has the power to fire Mueller. Additionally, in recent days, Trump has routinely referred to the investigation as "conflicted," "corrupt," "a total witch hunt," and the raid on Cohen's office as "unthinkable."