Hillary Clinton’s election campaign manager has criticised the FBI following reports that the security organisation was aware of potential links between the Trump administration and Russian officials while it was investigating Ms Clinton’s use of a private email server.

In a tweet on Tuesday, Robby Mook, who headed up Ms Clinton’s election campaign, wrote: “I'd like the FBI to explain why they sent a letter about Clinton but not this,” along with a New York Times article about the Trump administration’s “repeated contacts” with Russian intelligence.

Mr Mook was referring to a letter presented by FBI director James Comey prior to the election, which stated that new material was being studied in an investigation of Ms Clinton’s use of a private internet server for her emails — a move the Clinton campaign team claim cost her crucial votes.

By contrast, Mr Mook points out in his tweet, the Republican Mr Comey said nothing at the time about the newly emerged allegations of Mr Trump's Russian links, which were also being investigated.

Hillary Clinton warned us about Russia’s interference with the US

Shortly after posting the tweet, Mr Mook posted another one questioning Jason Chaffetz, chairman of the US House Committee on Oversight and Government Reform, over whether the allegations would be heard in Congress, asking: "Will you protect USA or GOP (Republican Party)?”

“Mr. Chaffetz, if Trump staff dialog with Russia while Russia hacks Dems doesn't get a Congress hearing, what does? Will you protect USA or GOP?” the tweet read.

Ms Clinton’s campaign spokesman, Brian Fallon, followed a similar line but went further to describe the situation as a “collosal scandal". He wrote: “Everything we suspected during the campaign is proving true. This is a colossal scandal."

The New York Times reported on Tuesday that American law enforcement and intelligence agencies found “repeated contacts” between Mr Trump’s campaign staff and associates and senior Russian intelligence operatives in the year leading up to the election — actions prominent Democrats have since said could amount to treason.

The communications were reportedly intercepted at the same time evidence of Russian involvement in the Democratic National Committee (DNC) hack was discovered, although officials said they found no evidence of the Trump team “colluding” with Russia on efforts to influence the result.

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The claims surfaced following Michael Flynn’s resignation as national security advisor, after it emerged that in separate phone calls he had discussed sanctions with a Russian diplomat before Mr Trump took office, and indicated the relationship between the two countries would improve under a new administration.

Mr Flynn had originally denied discussing sanctions, but when it emerged that US intelligence officials had been monitoring the call to the Russian Ambassador to Washington, he had to reverse course.