Donald Trump’s team has been accused of possible “treason” as new allegations emerge of repeated contact with Russian intelligence officials during the US election campaign.

The President’s representatives have repeatedly denied any untoward contact with the Kremlin but fresh claims have emerged in the wake of a separate scandal that sparked the national security adviser's resignation.

The New York Times reported 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.

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.

Seth Moulton, a former US Marine and Democratic member of the House of Representatives, said the unconfirmed allegations could amount to “treason”.

“Russia is the number enemy of the US,” he told CNN. “If members of the administration are essentially conspiring with Russia - either through the campaign earlier or now in the administration itself…that’s the very definition of treason.”

The claims emerged as senior Republicans called for an independent investigation into Michael Flynn's links with Russia, following his resignation as national security adviser.

Senate Republican whip John Cornyn called for a probe, while John McCain, Chairman of the Senate Armed Services Committee, said Mr Flynn's resignation was a “troubling indication of the dysfunction of the current national security apparatus” and raised questions over Mr Trump's stance.

Paul Manafort denied the allegations, which have not been confirmed (Getty)

Other Republicans argued that as both the Senate and House intelligence committees are already examining alleged Russian interference in the election, there was no need for a separate probe.

Law enforcement officials did not say to what extent alleged contacts between Mr Trump's team and Russian intelligence may have been about business, the New York Times reported, and did not disclose details of what was discussed or how many people were involved.

Several of Mr Trump’s associates were implicated but the report named only one – Paul Manafort – what chaired the President’s election campaign for several months last year.

He previously worked as a political consultant for the former Ukrainian President, Viktor Yanukovych, before and after he fled to Russia during anti-government protests that preceded the country’s civil war.

Mr Manafort dismissed the latest claims as “absurd”, saying he had “never knowingly spoken to Russian intelligence officers” or been involved with the country’s government.

Sean Spicer, the White House spokesman, repeated denials of improper contact between Trump aides and Russia at a press briefing before the New York Times report emerged on Tuesday.

He described phone calls with the Russian ambassador that caused the resignation of Mr Flynn as an “isolated incident”, where he gave “incomplete information” to the Vice President over whether sanctions were discussed.

Asked whether the Trump administration was undertaking efforts to examine contacts with Russia, Mr Spicer said there was “no new information”.

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When challenged specifically on discussions held during the campaign, Mr Spicer said: “There’s nothing that would conclude me…that anything different has changed with respect to that time period.”

Mike Pence, the Vice President, also denied contact had taken place with Russia before the election in a Fox News interview on Sunday.

“Of course not. Why would there be any contact between the campaign?” he said. “This is all a distraction, and it's all part of a narrative to delegitimise the election.”

In November, Russia’s deputy foreign minister Sergei Ryabkov said there had been communication between the Russian government and members of Mr Trump’s political team.

“There were contacts,” he told Interfax. “We are doing this and have been doing this during the election campaign.

”Obviously, we know most of the people from his entourage…quite a few have been staying in touch with Russian representatives.“

But Hope Hicks, the spokesperson for the President’s campaign, issued a denial saying members "had no contact with Russian officials".

In a press conference in January, Mr Trump did not directly answer demands to state whether his aides had been in contact with Russia in during his run for office.

On the same day, he tweeted: “Russia has never tried to use leverage over me. I HAVE NOTHING TO DO WITH RUSSIA - NO DEALS, NO LOANS, NO NOTHING!”

As controversy swirled over Mr Flynn’s resignation on Tuesday, the President said the “real story here is why are there so many illegal leaks coming out of Washington”.

President Donald Trump speaks on the phone with Russian President Vladimir Putin in the Oval Office of the White House (Getty Images) (Getty)

The intercepts have alarmed US intelligence and law enforcement agencies, in part because of the amount of contact that was occurring while Mr Trump was speaking glowingly about Vladimir Putin.

The pair have vowed to repair ties between the US and America and have spoken on the phone ahead of a meeting expected later this year.

Several of Mr Trump’s associates have had business dealings with Russia, including the Secretary of State Rex Tillerson in his former role as CEO of Exxon Mobil.

Vladimir Jabbarov, a Russian senator, told state media the revelations were part of an intelligence community conspiracy to have the President impeached.

“This is a common tactic to try to discredit a particular person,” he added.

Mr Spicer said the President has been “incredibly tough on Russia”, adding: “President Trump has made it very clear that he expects the Russian government to de-escalate violence in the Ukraine and return Crimea.

“At the same time, he fully expects to and wants to be able to get along with Russia, unlike previous administrations, so that we can solve many problems together facing the world, such as the threat of Isis and terrorism.”