Senior Russian intelligence and political officials discussed how to influence Donald Trump through his advisers according to information gathered by American spies last summer, the New York Times reported on Wednesday,

Citing three current and former U.S. officials familiar with the intelligence, the newspaper said the conversations focused on Paul Manafort, then the Mr. Trump presidential campaign chairman, and Michael Flynn, a retired general who was then advising Mr. Trump.

U.S. congressional committees and a special counsel named by the Justice Department this month are investigating whether there was Russian interference in the 2016 U.S. election and the possibility of collusion between Mr. Trump's campaign and Russia.

The controversy has engulfed Mr. Trump's young administration since he fired FBI Director James Comey two weeks ago amid the agency's investigation of possible Russia ties. Moscow has repeatedly denied the allegations and Mr. Trump denies any collusion.

The New York Times report was the latest indication of the depth of concerns within the U.S. intelligence community about Russian efforts to tip November's election toward Mr. Trump as he battled Democrat Hillary Clinton.

On May 18, Reuters reported that Mr. Flynn and other advisers to Mr. Trump’s campaign were in contact with Russian officials and others with Kremlin ties in at least 18 calls and emails during the last seven months of the 2016 presidential race, citing current and former U.S. officials.

On Tuesday, former CIA Director John Brennan told lawmakers he had noticed contacts between associates of Mr. Trump's campaign and Russia during the campaign and grew concerned Moscow had sought to lure Americans down “a treasonous path.”

In its report, the New York Times said some Russians boasted about how well they knew Mr. Flynn, who was subsequently named Mr. Trump's national security adviser before being dismissed less than a month after the Republican took office.

Others discussed leveraging their ties to Viktor Yanukovych, the deposed President of Ukraine living in exile in Russia, who at one time had worked closely with Manafort, who was dismissed from Mr. Trump's campaign, the newspaper reported.

Former Trump aide to testify

Separately, Carter Page, a former foreign policy adviser to Mr. Trump's presidential campaign, told Reuters via text message that he would testify before the House Intelligence Committee but was “still working out details.”

“Nothing (is) fully confirmed at this stage,” Mr. Page wrote, adding that if invited, he would also testify before the Senate Intelligence Committee, but had yet to receive such a request.

ABC News, which first reported on Page's planned testimony, said he would testify before the House panel on June 6. A spokesman for the committee declined comment on whether Mr. Page would testify.

In a letter to the panel seen by Reuters, Mr. Page accused Mr. Brennan of offering a “biased viewpoint” in Tuesday's testimony.

On Wednesday morning, the top Democrat on the committee said it would subpoena Mr. Flynn in its probe into alleged Russian meddling in the presidential election after he declined to appear before the panel.

“We will be following up with subpoenas, and those subpoenas will be designed to maximize our chance of getting the information that we need,” Representative Adam Schiff told journalists at a breakfast sponsored by the Christian Science Monitor.

The leaders of the U.S. Senate Intelligence Committee said on Tuesday they would subpoena two of Mr. Flynn's businesses after he declined to hand over documents in its separate Russia probe.

Mr. Flynn, a retired general, is a key witness in the Russia investigations because of his ties to Moscow.

He was fired from his position at the White House in February, after less than a month on the job, for failing to disclose the content of talks with Sergei Kislyak, Russia's Ambassador to the United States, and misleading Vice-President Mike Pence about the conversations.