"Why is that Hillary Clintons family and Dems dealings with Russia are not looked at, but my non-dealings are?" the President tweeted, adding, "Crooked H destroyed phones w/ hammer, 'bleached' emails, & had husband meet w/AG days before she was cleared- & they talk about obstruction?"

The tweets may be in reference to reports from the FBI's investigation into Ms Clinton's private email sever. The reports, released last year, say Ms Clinton destroyed her used phones on at least two occasions while serving as secretary of state. She also used BleachBit software to delete some of her emails.

Mr Trump's rehashing of these reports came one day after The Washington Post reported that he is under investigation for obstruction of justice.

The Post reported on Wednesday that Robert Mueller – the special counsel overseeing the investigation into Russian meddling in the US election – was looking into the President's possible interference in that investigation.

Mr Trump issued a separate string of tweets following this revelation, calling the investigation into his conduct "the single greatest WITCH HUNT in American political history - led by some very bad and conflicted people!"

"They made up a phony collusion with the Russians story, found zero proof, so now they go for obstruction of justice on the phony story," he wrote. "Nice."

The President has faced criticism from Democrats and Republicans alike, after unexpectedly firing the FBI director in charge of investigating his campaign's potential ties to Russia.

Former FBI Director James Comey later alleged tht Mr Trump had instructed him to drop investigations into members of his campaign team, and referred to the Russian investigation as a "cloud" he would like to see lifted.

Mr Comey's revelations were one of the key reasons a special prosecutor was appointed to oversee the investigation in his place.

Ms Clinton also stirred controversy during her time as secretary of state, most notably for using a private email server to house her professional emails.

The FBI's investigation into this email server became a fixture of the 2016 presidential election, and a favourite talking point of Mr Trump.

At one point, Ms Clinton's husband boarded a plane with the Attorney General shortly before the Justice Department was set to announce its findings. This incident – which sparked public outcry and prompted the FBI to cut the Justice Department out of the announcement – appears to be what Mr Trump referenced in his most recent tweet.

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