Naxos, Italy (CNN) President Donald Trump's top economic and national security advisers on Saturday declined to comment on the swirl of allegations that Trump's son-in-law and senior adviser Jared Kushner is facing regarding his contacts with Russian officials.

Kushner discussed creating a secret communications channel between the Trump transition team and the Kremlin with Russia's ambassador Sergey Kislyak, a source with knowledge of the matter confirmed to CNN after The Washington Post reported Friday , citing US officials briefed on intelligence reports.

Lt. Gen. H.R. McMaster, the national security adviser, declined to say whether he would be concerned if a private citizen attempted to set up backchannel communications with a foreign government to influence US foreign policy and said he would not be concerned if a White House official attempted to do so.

"We have backchannel communications with a number of countries," McMaster said.

McMaster and Gary Cohn, the director of the National Economic Council, swatted away the questions after reports surfaced that Kushner considered setting up a secret line of communication with Russia to discuss military options in Syria and other matters. A source with knowledge of the matter confirmed to CNN that Kushner first discussed creating the backchannel in a meeting last December with the Russian ambassador.

Kushner was a private citizen at the time, not a US government official although he was acting on behalf of the incoming US government and in an official capacity having an interim security clearance.

The details were shared with CNN as an explanation to The Washington Post reporting, which it said was based on intercepts of conversations between Russia's ambassador and Moscow.

Kislyak, according to The Post, told higher-ups in Moscow that Kushner suggested the proposal in a December meeting at Trump Tower -- which former national security adviser Michael Flynn also attended. Kushner "suggested using Russian diplomatic facilities in the United States for the communications," the Post reported, in an apparent attempt to try to shield discussions during the transition from monitoring.

The Post said Kislyak reportedly was taken aback by the idea of having an American use Russian communications equipment at one of its facilities because it could have involved security risks for both Americans and Russians.

Such a line of communication would have allowed Kushner and Flynn to talk securely with Russian military officials, but it never was actually set up, the source with knowledge of the matter confirmed to CNN. Flynn apparently would have been the US point person, the source said.

"That's something I'm not prepared to talk about," McMaster said when he was first asked about the allegations.

Cohn said: "We're not going to comment on Jared. We're just not going to comment."

Pressed repeatedly on the matter during a news conference on Saturday that was kept off camera at the White House's insistence, McMaster also said he was not "involved with or have any knowledge of" any attempt on Kushner's part to set up backchannel communications with Moscow.

The FBI, in the course of its investigation into Russian involvement in the 2016 election, is now also looking at Kushner's multiple roles in Trump's campaign operation and his contacts with Russian officials.

Kushner has acknowledged meeting during the transition with the Russian ambassador to Washington, but Reuters, citing seven current and former US officials, reported Friday that Kushner had several previously undisclosed contacts with Russia's ambassador -- including two phone calls between April and November of 2016.

Kushner's lawyer, Jamie Gorelick, told CNN in response to the Reuters report: "Mr. Kushner participated in thousands of calls in this time period. He has no recollection of the calls as described. We have asked (Reuters) for the dates of such alleged calls so we may look into it and respond, but we have not received such information."

A White House official close to Kushner pushed back on any notion that Kushner would take leave from his West Wing duties in light of recent reports. This official said Kushner will keep his head down and stay focused on his work. Kushner is eager to cooperate with any and all inquiries, this official said.

McMaster was visibly frustrated as he faced a barrage of questions from reporters on Saturday about Kushner's contacts with the Russians. He urged reporters to instead ask him about foreign policy and national security issues that would have come up during the President's first foreign trip, which has been dogged by the incessant flow of new allegations surrounding the President's campaign associates' contacts with Russian officials.

This story has been updated.