Robert Mueller has revealed "several" investigations are still ongoing connected to the probe into Russia's interference in the 2016 election of Donald Trump, contradicting widespread reports the process had effectively been concluded.

In a filing with the US District Court in Washington, US Special Counsel Robert Mueller cited Mr Trump's former deputy campaign chairman Rick Gates’ continued cooperation with multiple probes and asked permission to update the judge on the case again by May 14.

“Gates continues to cooperate with respect to several ongoing investigations, and accordingly the parties do not believe it is appropriate to commence the sentencing process at this time,” Mr Mueller’s team said in the court filing.

Gates is one of several advisers to the president who have been charged or pleaded guilty to crimes stemming from the federal investigation into alleged Russian interference in the 2016 US presidential election and possible collusion with Mr Trump’s campaign.

Gates was the longtime business partner of the president's campaign chairman Paul Manafort, who faces more than seven years in prison for financial and conspiracy crimes after sentencing this week in a separate case in federal court in Washington.

Criminals who worked for Trump Show all 5 1 /5 Criminals who worked for Trump Criminals who worked for Trump Michael Cohen Former lawyer for Donald Trump was sentenced to three years in prison on counts involving evading income tax, false disclosure of the hush money paid to Stormy Daniels and another hush money charge Getty Criminals who worked for Trump Paul Manafort Former campaign manager for Trump Manafort was found guilty in February 2018 of five counts of tax fraud, two counts of bank fraud and one count of failure to disclose a foreign bank account. The crimes occurred prior to his appointment in Trump's campaign Getty Criminals who worked for Trump George Papadopoulos Former Trump campaign adviser Papadopoulos pleaded guilty to lying to the FBI in October 2017. He had lied about making contact with a professor who claimed that the Russians had dirt on Hillary Clinton. He was sentenced to 14 days in jail Getty Criminals who worked for Trump Michael Flynn Former White House National Security adviser Michael Flynn pleaded guilty to lying to the FBI in December 2017. He had lied about conversations that he had with the Russian ambassador to the US during Trump's Presidential campaign. He was not given prison time due to his "significant assistance" to the Mueller investigation Getty Criminals who worked for Trump Rick Gates Deputy chairman of Trump's presidential campaign Gates pleaded guilty to lying to the FBI in February 2018 AFP/Getty

Unlike Manafort, who stood trial and was found guilty in one case in Virginia before pleading guilty in another case in Washington, Gates agreed early on to cooperate with Mr Mueller’s team and took the stand to testify against his former business partner.

Gates pleaded guilty in February 2018 to conspiracy against the United States and lying to investigators.

Russia has denied meddling in the 2016 US election. Mr Trump has said there was no collusion between his campaign and Moscow, and has characterised the special counsel's probe as a “witch hunt.”

He once again lambasted the special counsel’s investigation into Russian interference in the 2016 election on Twitter, suggesting it was created under shady circumstances.

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“So, if there was knowingly & acknowledged to be ‘zero’ crime when the Special Counsel was appointed, and if the appointment was made based on the Fake Dossier (paid for by Crooked Hillary) and now disgraced Andrew McCabe (he & all stated no crime), then the Special Counsel should never have been appointed and there should be no Mueller Report," the president wrote. "This was an illegal & conflicted investigation in search of a crime. Russian Collusion was nothing more than an excuse by the Democrats for losing an Election that they thought they were going to win."