Donald Trump will on Saturday return from his first overseas trip as president, a nine-day, multicity tour of the Middle East and Europe, to find Washington roiled by the latest revelations in the Russia investigation.

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During a press briefing at the G7 conference in Taormina, Sicily, White House officials refused to comment directly on a Washington Post report that Jared Kushner, the president’s son-in-law and senior adviser, discussed setting up a secret back channel for conversations between the Trump transition team and the Kremlin.

“We’re not going to comment on Jared – we’re just not,” Gary Cohn, the White House economic adviser, told reporters after repeated questions, in an attempt to steer the focus back to Trump’s overseas trip.

HR McMaster, Trump’s national security adviser, also refused to comment on the story specifically but said that he was “not concerned”.

“We have back-channel communications with a number of countries so, generally speaking about back-channel communications, what that allows you to do is to communicate in a discreet manner,” McMaster said.

According to the Post, citing intercepts of communications reviewed by US officials, Russian ambassador Sergei Kislyak told superiors in Moscow that Kushner proposed setting up the channel, meant to shield pre-inauguration discussions from monitoring by US intelligence officials, during a December meeting at Trump Tower in New York City.

During his campaign, Trump repeatedly called for a reset of US-Russia relations, and raised concerns with flattering remarks about Russian president Vladimir Putin. After the election, US intelligence agencies concluded that Russia interfered in the campaign in an effort to undermine Trump’s opponent, Hillary Clinton. The FBI and several congressional committees are investigating contacts between Trump aides and Russian officials.

The Post report on Kushner added the caveat that “Russia at times feeds false information into communication streams it suspects are monitored as a way of sowing misinformation and confusion among US analysts.” But officials said it was unclear what Kislyak would gain by mischaracterizing a conversation with Kushner, especially given the prospect of improving relations between the two countries.

Earlier this week it was reported that the FBI is looking into Kushner’s contacts with Russia, a first sign that the investigation has reached not only the president’s inner circle but his family. According to the Post, the FBI considers the Trump Tower meeting between Kushner and Kislyak, which the White House disclosed in March, of “investigative interest”.

Kushner has not commented but through a lawyer has said he will cooperate in the investigation.

“Mr Kushner previously volunteered to share with Congress what he knows about these meetings,” attorney Jamie Gorelick said in a statement on Thursday. “He will do the same if he is contacted in connection with any other inquiry.”

Following the Post’s report on Friday, two other news outlets published stories related to the Trump campaign and Russia.

Reuters, citing seven current and former US officials, reported that Kushner had at least three previously undisclosed contacts with Kislyak during and after the 2016 election, including two phone calls between April and November. In response, Kushner’s attorney said Kushner did not remember any calls with Kislyak between April and November.

“Mr Kushner participated in thousands of calls in this time period. He has no recollection of the calls as described,” Gorelick said. “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.”

Kislyak has emerged as a central figure in several Russia-related controversies. In February, Michael Flynn, Trump’s first national security adviser, resigned after misleading the administration about his contacts with Russia, including extensive communications with the ambassador. Attorney General Jeff Sessions later recused himself from overseeing the FBI investigation into Russia after failing to disclose two meetings with Kislyak.

In a 10 May meeting in the Oval Office, held the day after Trump fired FBI director James Comey, Trump reportedly relayed highly sensitive information about the Islamic State in Syria to Kislyak and Russian foreign minister Sergei Lavrov.

In a recent media appearance with Israeli prime minister Benjamin Netanyahu, Trump denied telling Russian officials the classified information had come from Israeli intelligence.

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“I never mentioned the word or the name Israel,” Trump said. “Never mentioned it during that conversation. They’re all saying I did, so you have another story wrong. Never mentioned the word Israel.”

That was never the charge. Reports said Trump, boasting about his access to “great intel” during his meeting with the Russians, had shared enough information for the Russians to glean the identity of the source.

On his first overseas trip, Trump visited ancestral homelands of three of the world’s largest monotheistic religions and also attended the Nato summit in Brussels. Breaking with precedent for presidents abroad, he did not host a news conference. Before leaving for Washington, he addressed US service members at Sigonella Naval Air Station, in Sicily.

Once the president is home, his administration will be forced to respond to the spate of damaging reports that have led some Democrats in Congress to call for impeachment proceedings.

Trump’s team said a campaign-style rally planned for Cedar Rapids, Iowa on Thursday had been postponed “due to an unforeseen change” in the president’s schedule. They did not elaborate.