Documentary filmmaker Michael Moore has branded Donald Trump a “Russian traitor” and called for his impeachment as the scandal surrounding contact between the President's advisers and Moscow deepened.

In the wake of National Security Adviser Michael Flynn's resignation over his inappropriate contact with Moscow in recent weeks, now phone records and intercepted calls allegedly show members of the Trump campaign had repeated contact with senior Russian intelligence agents in the year running up to the election, four US officials told the New York Times.

The claims, which have been reported by the New York Times and come from four unnamed US officials, have prompted the outspoken filmmaker to call on Mr Trump to step down. He tweeted: "Um, @realDonaldTrump -- It's now noontime in DC & it appears you are still squatting in our Oval Office. I gave u til this morning to leave."

"What part of 'vacate you Russian traitor' don't you understand? We can do this the easy way (you resign), or the hard way (impeachment)," he later added.

Mr Moore has been an outspoken critic of the Republican President, releasing a documentary shortly before the 2016 election about the then-Presidential candidate, and he has repeatedly questioned his ties to Russia.

Reports of the Trump campaign's phone calls with Russia come the day after Mr Trump’s national security adviser, Michael Flynn, was forced for resign over conversations with the Russian ambassador to Washington and subsequent misrepresentations he gave of those discussions.

In a resignation letter, Mr Flynn said he gave Vice President Mike Pence and others "incomplete information" about his calls with Russia's ambassador to the US.

Apparently relying on this information, Mr Pence initially said the national security adviser had not discussed sanctions with the Russian envoy, although Mr Flynn later conceded the issue may have come up.

Michael Moore: Trump will 'break laws'

The former lieutenant general's resignation letter said that he held numerous calls with "foreign counterparts, ministers, and ambassadors [...] to facilitate a smooth transition".

It has emerged Mr Trump was told several weeks ago that Mr Flynn had not told the truth about a phone call with a Russian diplomat.

White House Press Secretary Sean Spicer said firing Mr Flynn was an issue of "trust" and not whether it was a legal problem.

"The irony is President Trump has been very tough on Russia," he told reporters on Tuesday.

Trump and Putin passionately kiss in street mural Show all 14 1 /14 Trump and Putin passionately kiss in street mural Trump and Putin passionately kiss in street mural A lesbian couple kisses in front of mural depicting Russian President Vladimir Putin and Republican presidential candidate Donald Trump, on the walls of a barbecue bar 'Keule Ruke' on May 19, 2016 in Vilnius, Lithuania. Barcroft Media/Getty Trump and Putin passionately kiss in street mural A lesbian couple kisses in front of mural depicting Russian President Vladimir Putin and Republican presidential candidate Donald Trump, on the walls of a barbecue bar 'Keule Ruke' on May 19, 2016 in Vilnius, Lithuania. Barcroft Media/Getty Trump and Putin passionately kiss in street mural VILNIUS, LITHUANIA - NOVEMBER 23: A woman walks past a mural showing U.S. President-elect Donald Trump (R) blowing marijuana smoke into the mouth of Russian President Vladimir Putin on the wall of a bar-b-que restaurant on November 23, 2016 in Vilnius, Lithuania. Many people in the three Baltic nations of Lithuania, Latvia and Estonia are concerned that Russia, because Trump has expressed both admiration for Putin and doubt over defending NATO member states, will be emboldened to intervene militarily in the Baltics. Sean Gallup/Getty Trump and Putin passionately kiss in street mural A woman walks past a mural on a restaurant wall depicting US Presidential hopeful Donald Trump and Russian President Vladimir Putin greeting each other with a kiss in the Lithuanian capital Vilnius on May 13, 2016. Kestutis Girnius, associate professor of the Institute of International Relations and Political Science in Vilnius university, told AFP -This graffiti expresses the fear of some Lithuanians that Donald Trump is likely to kowtow to Vladimir Putin and be indifferent to Lithuanias security concerns. Trump has notoriously stated that Putin is a strong leader, and that NATO is obsolete and expensive. Petras Malukas/AFP/Getty Images Trump and Putin passionately kiss in street mural AP Trump and Putin passionately kiss in street mural A child walks past a graffiti depicting Russian President Vladimir Putin, left, and Republican presidential candidate Donald Trump, on the walls of a bar in the old town in Vilnius, Lithuania, Saturday, May 14, 2016. (AP Photo/Mindaugas Kulbis) AP Trump and Putin passionately kiss in street mural People walk past a mural on a restaurant wall depicting US Presidential hopeful Donald Trump and Russian President Vladimir Putin greeting each other with a kiss in the Lithuanian capital Vilnius on May 13, 2016. Kestutis Girnius, associate professor of the Institute of International Relations and Political Science in Vilnius university, told AFP -This graffiti expresses the fear of some Lithuanians that Donald Trump is likely to kowtow to Vladimir Putin and be indifferent to Lithuanias security concerns. Trump has notoriously stated that Putin is a strong leader, and that NATO is obsolete and expensive. Petras Malukas/AFP/Getty Images Trump and Putin passionately kiss in street mural A man photographs a mural on a restaurant wall depicting US Presidential hopeful Donald Trump and Russian President Vladimir Putin greeting each other with a kiss in the Lithuanian capital Vilnius on May 13, 2016. Kestutis Girnius, associate professor of the Institute of International Relations and Political Science in Vilnius university, told AFP -This graffiti expresses the fear of some Lithuanians that Donald Trump is likely to kowtow to Vladimir Putin and be indifferent to Lithuanias security concerns. Trump has notoriously stated that Putin is a strong leader, and that NATO is obsolete and expensive. Petras Malukas/AFP/Getty Images Trump and Putin passionately kiss in street mural AP Trump and Putin passionately kiss in street mural A young woman walks past a mural showing U.S. President-elect Donald Trump (R) blowing marijuana smoke into the mouth of Russian President Vladimir Putin with the slogan "make everything great again," in reference to Trump's campaign slogan of "Make America Great Again," on the wall of a bar-b-que restaurant on November 23, 2016 in Vilnius, Lithuania. Many people in the three Baltic nations of Lithuania, Latvia and Estonia are concerned that Russia, because Trump has expressed both admiration for Putin and doubt over defending NATO member states, will be emboldened to intervene militarily in the Baltics. Sean Gallup/Getty Trump and Putin passionately kiss in street mural A morning commuter stops to look at a mural on a restaurant wall depicting US Presidential hopeful Donald Trump and Russian President Vladimir Putin greeting each other with a kiss in the Lithuanian capital Vilnius on May 13, 2016. Kestutis Girnius, associate professor of the Institute of International Relations and Political Science in Vilnius university, told AFP -This graffiti expresses the fear of some Lithuanians that Donald Trump is likely to kowtow to Vladimir Putin and be indifferent to Lithuanias security concerns. Trump has notoriously stated that Putin is a strong leader, and that NATO is obsolete and expensive. Petras Malukas/AFP/Getty Images Trump and Putin passionately kiss in street mural Restaurant owner Dominykas Ceckauskas pose next to a mural on the wall of his establishment depicting US Presidential hopeful Donald Trump and Russian President Vladimir Putin greeting each other with a kiss in the Lithuanian capital Vilnius on May 13, 2016. Kestutis Girnius, associate professor of the Institute of International Relations and Political Science in Vilnius university, told AFP -This graffiti expresses the fear of some Lithuanians that Donald Trump is likely to kowtow to Vladimir Putin and be indifferent to Lithuanias security concerns. Trump has notoriously stated that Putin is a strong leader, and that NATO is obsolete and expensive. / AFP / Petras Malukas (Photo credit should read PETRAS MALUKAS/AFP/Getty Images) Petras Malukas/AFP/Getty Images Trump and Putin passionately kiss in street mural A passerby photographs a mural showing U.S. President-elect Donald Trump (R) blowing marijuana smoke into the mouth of Russian President Vladimir Putin on the wall of a bar-b-que restaurant on November 23, 2016 in Vilnius, Lithuania. Many people in the three Baltic nations of Lithuania, Latvia and Estonia are concerned that Russia, because Trump has expressed both admiration for Putin and doubt over defending NATO member states, will be emboldened to intervene militarily in the Baltics. Sean Gallup/Getty Trump and Putin passionately kiss in street mural Getty

Sources for The New York Times did not say which individuals Mr Trump's circles spoke with Russian officials, including government members. The only name mentioned was Paul Manafort's, Mr Trump's former campaign manager who resigned after a few months over revelations that he had worked as a political consultant in Russia and Ukraine.

Mr Spicer said on Monday said "there is nothing that would conclude me that anything has changed during that time period", answering a question about whether any Trump campaign members had talked to Russian operatives during the campaign.