White House officials and Republicans close to the administration say Trump, who campaigned on an "America First" slogan, wants to demonstrate leadership overseas on his visit with Arab leaders in Saudi Arabia, Israeli and Palestinian leaders in Israel and the West Bank, the pope at the Vatican, North Atlantic Treaty Organization leaders in Brussels and Group of Seven counterparts in Sicily.
Mr Trump appointed Mr Flynn as his national security adviser weeks later despite the warning, but he was sacked after just 24 days.
Lavrov didn't directly confirm details of their conversation.
Comey prepared extensively for his discussions with President Trump, out of concern that the president was unlikely to respect the legal and ethical boundaries governing their respective roles, according to associates of the now-fired Federal Bureau of Investigation chief.
Burr, the Senate intelligence panel's chairman, said they are awaiting word from Flynn's attorneys whether he will comply with a subpoena for his records. Burr of North Carolina.
Flynn was ousted in mid-February after less than a month in his senior administration post.
Deputy attorney general Rod Rosenstein appointed Robert Mueller to serve as a special counsel for the United States Department of Justice this week, authorizing him to continue the investigation led by former FBI director James Comey into any ties between Russian government officials and individuals associated with the campaign of U.S. President Donald Trump.
Democrats have made unfounded allegations of collusion between the Trump campaign and Russian Federation even though former Obama administration officials, such as former Director of National Intelligence, James Clapper, have testified under oath that no such evidence exists. Trump later deleted and retweeted that statement to correct the spelling of "counsel".More news: Anthony Weiner leaves court after guilty plea
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He did not provide examples or evidence of any alleged "illegal acts".
The FBI and Congress are looking into potential links between Mr Trump's campaign team and Russian Federation.
On Wednesday, the Justice Department appointed former FBI Director Robert Mueller as a special counsel to lead the probe into Russian interference in the 2016 USA election.
White House officials have disputed the accuracy of a memo Comey wrote describing what was said at the January dinner.
Mueller will have sweeping powers and the authority to prosecute any crimes he uncovers.
The surprise announcement to hand the probe over to Mueller, a lawman with deep bipartisan respect, was a striking shift for Trump's Justice Department, which had resisted increasingly loud calls from Democrats for an outside prosecutor.
A day earlier, as the featured speaker at the Coast Guard Academy's commencement exercises, Trump had similarly voiced the belief that "no politician in history. has been treated worse or more unfairly".