Donald Trump has described the probe into alleged Russian meddling in the 2016 US presidential election as a "witch hunt", amid reports the first charges in the criminal investigation could be laid as early as today.

Key points: The outburst follows reports that charges in the Russia probe have been approved

The outburst follows reports that charges in the Russia probe have been approved Mr Trump tweets for someone to "DO SOMETHING!" about the "phony" probe

Mr Trump tweets for someone to "DO SOMETHING!" about the "phony" probe Intelligence agencies have already confirmed Russia meddled in the 2016 election

"All of this 'Russia' talk right when the Republicans are making their big push for historic Tax Cuts & Reform. Is this coincidental? NOT!," Mr Trump wrote on Twitter.

He added that Democrats are using the Russian "witch hunt" for "evil politics", while adding that Republicans are "fighting back like never before".

Mr Trump's latest tweets follow reports over the weekend that a federal grand jury in Washington had approved the first charges in the criminal investigation led by special counsel Robert Mueller.

The indictment was sealed under orders from a federal judge, but has been reported by US media outlets citing sources who said they had been briefed on the matter.

It was not clear what the charges were or who the target was, with reports adding the indictment could be unsealed as early as today.

In his latest Twitter outburst, Mr Trump again raised accusations based on reports from last week that Mrs Clinton's campaign and the Democrats helped fund a shocking dossier that contained salacious material about the US President, while also raising other accusations against the Clintons.

"Never seen such Republican ANGER & UNITY as I have concerning the lack of investigation on Clinton made Fake Dossier (now $12,000,000?), the Uranium to Russia deal, the 33,000 plus deleted Emails, the Comey fix and so much more," he wrote.

"Instead they look at phony Trump/Russia 'collusion,' which doesn't exist.

"The Dems are using this terrible (and bad for our country) Witch Hunt for evil politics, but the R's [Republicans] are now fighting back like never before.

"There is so much GUILT by Democrats/Clinton, and now the facts are pouring out. DO SOMETHING!"

US intelligence agencies have already concluded that Russia interfered in the election to try to help Mr Trump defeat Mrs Clinton through a campaign of hacking, and disseminating propaganda via social media to discredit her campaign.

Mr Trump denied allegations his campaign colluded with Russians and condemned investigations into the matter. The Kremlin has also denied the allegations.

The special counsel's investigation also includes an effort to determine whether the President or any of his aides tried to obstruct justice.

Money laundering, financial crimes points of interest

Mr Mueller, a former director of the Federal Bureau of Investigation, has been looking into possible links between Trump aides and foreign governments, as well as potential money laundering, tax evasion and other financial crimes, according to sources familiar with the probe.

He also is exploring whether Mr Trump or his aides have tried to obstruct the investigation.

Mr Mueller was appointed to lead the investigation a week after Mr Trump's May 9 firing of FBI Director James Comey, who was heading a federal probe into possible collusion with Russia.

Investigators have interviewed former White House chief of staff Reince Priebus, former spokesman Sean Spicer and other current and former White House and campaign officials.

In July, FBI agents raided the Virginia home of Mr Trump's former campaign manager Paul Manafort, whose financial and real estate dealings and prior work for a pro-Russian political party in Ukraine are being investigated by Mr Mueller's team.

Mr Mueller also has investigated Michael Flynn, an adviser to Mr Trump's campaign and later his national security adviser.

ABC/Wires