iStock/Thinkstock(MOSCOW) — At least two Democrats on the House Intelligence Committee are calling for President Donald Trump’s national security adviser, Michael Flynn, to be suspended in the wake of allegations that he discussed the U.S. sanctions against Russia in a conversation with Moscow’s ambassador to the U.S. ahead of Trump’s inauguration.

The allegations raise “serious questions of legality and fitness for office,” the top Democrat on the committee, Rep. Adam Schiff of California, said in a statement Friday. If the allegations are proven true, Flynn “should no longer serve in this administration or any other.”

Another top Democrat, Rep. Eric Swalwell, also of California, said Flynn should step aside while the allegations are looked into.

“The White House should immediately SUSPEND National Security Advisor Flynn & REVOKE access to classified information until investigated,” Swalwell said in a statement online.

ABC News has confirmed that in the weeks before the inauguration, Flynn discussed the sanctions issue with Ambassador Sergey Kislyak, though current and former U.S. officials were not able to say whether those discussions included any promises to lift sanctions. The Washington Post first reported Thursday that Flynn discussed the sanctions with Kislyak during a series of phone calls in December.

The latest claims conflict with repeated denials by Flynn and other senior members of the Trump administration that Flynn had discussed the sanctions issue during the calls.

Some of the U.S. officials, who headed government agencies at the time of the calls, told the Post they were concerned there may have been an inappropriate and potentially illegal attempt by Flynn to reassure the Kremlin on sanctions as the Obama administration was imposing measures against Russia in retaliation for allegedly intervening in the U.S. presidential election.

Flynn has denied the claims, which ABC News has so far been unable to verify independently, saying initially the two had only exchanged Christmas greetings and discussed plans for a phone call between President Donald Trump and Russian President Vladimir Putin.

Sean Spicer, now the White House press secretary, told reporters last month, “They exchanged logistical information on how to initiate and schedule that call. That was it. Plain and simple.” Spicer later told ABC News that Kislyak had called to invite the U.S. to talks on the Syrian conflict that were held in Kazakhstan recently.

Flynn this week denied again that sanctions came up, but on Friday the White House appeared to be moving back from the denial: A senior administration official told ABC News that Flynn doesn’t recall any discussion of sanctions ever coming up with Kislyak, but isn’t completely certain.

Putin’s spokesman, Dmitry Peskov, confirmed that Flynn spoke by phone with Kislyak but said reports that they had discussed sanctions were “wrong.”

The questions over Flynn’s contacts with Kislyak were first raised in early January. Spicer told reporters that Flynn and the Russian ambassador talked by phone on Dec. 28. Spicer later told ABC News he misspoke and the call was on Dec. 29, the same day that President Obama expelled 35 Russian diplomats from the U.S. and closed a handful of Russian diplomatic facilities as punishment for the alleged Kremlin meddling.

Concerns were raised by some administration officials that Flynn may have sought to undermine those sanctions in his call with Kislyak. After the expulsions, the Kremlin unusually declined a tit-for-tat response, instead inviting American diplomats in Moscow to a children’s Christmas party.

The Trump administration has backed Flynn’s story.

In an interview last month, Vice President Mike Pence told CBS: “They did not discuss anything having to do with the United States’ decision to expel diplomats or impose censure against Russia.” A senior administration official told ABC News that Pence’s information on the case had come from speaking with Flynn directly.

The White House’s story on what the two did discuss has developed since the communications were first reported, with Spicer most recently saying four topics were discussed: the crash of a Russian military plane carrying an army choir on Christmas day, holiday greetings, the invitation to the Syrian talks and a potential Trump-Putin phone-call.

According to the Post, the FBI is examining Flynn’s communications with Kislyak. U.S. officials have said Flynn’s calls with Kislayk were picked up as part of routine surveillance of the Russian diplomat. According to the Post, further communications between Flynn and Kislyak were also conducted in person and by text message, details of which contradict the administration’s statements on them so far.

The Post and The New York Times have reported that another FBI investigation is also looking into possible contacts between three members of Trump’s campaign team during the election. The White House has denied being aware that any such investigation is underway. A senior administration official told ABC News last month that the White House has “absolutely no knowledge of any investigation or even a basis for such an investigation.”

Some of the officials in the Post story stressed the Obama administration was divided over how to interpret the calls. Several of the officials “emphasized that while sanctions were discussed, they did not see evidence that Flynn had an intent to convey an explicit promise to take action after the inauguration,” the Post said.

The Logan Act, the law which Flynn is accused of potentially violating, forbids U.S. citizens from interfering in foreign policy.

The administration’s contacts with Russia are under scrutiny after U.S. intelligence concluded that the Kremlin had intervened in the elections to help Trump and harm his Democrat opponent, Hillary Clinton. A declassified report from the Director of National Intelligence in December found Russia had used cyberattacks and propaganda to try to undermine American democracy and to tilt the balance in favor of Trump.

A broad Senate investigation is currently underway into the alleged interference; it is not clear whether the FBI’s investigation of Flynn is part of that.

Flynn’s attitude to Russia specifically has attracted criticism from some Democrats and Republicans, in particular a 2015 trip to Moscow to speak at an anniversary conference for the Russian propaganda network, Russia Today, where he dined at a table with Putin.

Publicly, including at the Moscow conference, Flynn has suggested he believes the U.S. should work with Russia to combat radical Islamic terrorism, which he has described as a “cancer.”

Congressional Democrats have written a letter to the Pentagon requesting more details on Flynn’s Moscow trip, seeking information on payments he received for speaking at the Russia Today conference.

“It is extremely concerning that General Flynn chose to accept payment for appearing at a gala hosted by the propaganda arm of the Russian government, which attacked the United States in an effort to undermine our election,” Rep. Elijah Cummings, the ranking Democrat on the House Committee on Oversight and Government Reform, wrote in the Feb. 1 letter.

Flynn has acknowledged that he was paid for speaking in Moscow, telling the Washington Post the invitation came through his speakers bureau.

ABC Breaking News | Latest News Videos

Copyright © 2017, ABC Radio. All rights reserved.