Russian collusion a "made-up hoax": Trump

US President Donald Trump today termed as "phony" the claims of a 'Russian collusion' in the 2016 presidential election, asserting that it was a "made-up hoax" as he slammed his opponents.

Trump's remarks came days after he claimed that a Justice Department watchdog report related to the 2016 election "totally discredited" the probe by Special Counsel Robert Mueller into possible Trump campaign collusion with the Russians.

"Witch Hunt! There was no Russian Collusion. Oh, I see, there was no Russian Collusion, so now they look for obstruction on the no Russian Collusion," Trump tweeted.

"The phony Russian Collusion was a made-up Hoax. Too bad they didn't look at Crooked Hillary like this. Double Standard!" he said.

The US Justice Department last month agreed to expand its investigation into alleged Russia collusion in the 2016 election to include "any irregularities" involving FBI tactics on Trump's presidential campaign.

Trump has not yet spoken to special counsel Robert Mueller as part of the probe.

Last month, Trump termed Mueller's probe into the allegations of Russian interference in the 2016 US elections as "the world's most expensive witch hunt" as he trashed a media report that said an emissary representing the governments of Saudi Arabia and the UAE offered help to his campaign.

Trump has repeatedly attacked the Mueller's investigation as a witch hunt and claims that the probe is biased against him.

Mueller is trying to determine if Trump's campaign advisers colluded with the Russian government to influence the election.

The investigation also reportedly involves a probe into whether the President obstructed justice when he allegedly asked ex-FBI director James Comey to drop an inquiry into former National Security Adviser Michael Flynn.

Flynn pleaded guilty in December to lying to the FBI about his conversations with the Russian ambassador, becoming the first senior White House official to cut a cooperation deal in Mueller's inquiry.