Former CIA Director John Brennan threw another log on the Trump-Russia controversy on Tuesday, testifying to House lawmakers that he saw intelligence linking Moscow to people involved with President Trump’s 2016 campaign.

“I encountered and am aware of information and intelligence that revealed contacts and interactions between Russian officials and U.S. persons involved in the Trump campaign that I was concerned about because of known Russian efforts to suborn such individuals,” Brennan said.

“It raised questions in my mind about whether Russia was able to gain the cooperation of those individuals,” he told members of the House Permanent Select Committee on Intelligence.

Trump in recent days has adamantly denied any claim of "collusion" with Russia, particularly in the wake of a special counsel being named to oversee the federal Russia probe.

Brennan said during Tuesday's open hearing he did not know whether Trump’s campaign “colluded” with Russia but said he saw "information and intelligence that was worthy of investigation.”

Brennan's comments were made during a tense exchange with Republican Rep. Trey Gowdy, who pressed the Obama-era official on what evidence he had of a "connection" between the Trump campaign and Russian state actors.

"As I said Mr. Gowdy, I don't do evidence," Brennan said.

The South Carolina congressman responded, "I appreciate that you don't do evidence, Director Brennan. Unfortunately, that's what I do."

Brennan said he could provide more information in closed session.

Brennan also testified that he warned Russia’s intelligence service director to stay out of the 2016 U.S. presidential elections – but that the warning was not heeded.

“It was clear to everyone Russia brazenly interfered and under explicit warning to not do so,” Brennan said.

On the Senate side, Director of National Intelligence Dan Coats declined to comment on a Washington Post story that claims Trump asked him to publicly deny evidence of Russian interference.

“I don’t feel it’s appropriate to characterize conversations with the president,” he told the Senate Armed Services Committee.

Brennan's testimony could undercut efforts by Trump and the White House to move past the Russia controversy and once again shift the spotlight to Trump’s domestic dilemmas as he continues his first foreign trip as commander-in-chief.

Tuesday’s testimony marked the first time Brennan, CIA director under former President Barack Obama, has publicly said he was worried about Russia and its ties to the Trump campaign. It also marks his first appearance before a congressional committee since leaving the CIA when President Trump took office in January.

The public hearing is also the House Intelligence Committee’s first since March 20, when then-FBI Director James Comey testified that the bureau is investigating Russian influence and possible collusion with members of Trump’s campaign.

Since then, Trump has fired Comey; the DOJ has appointed a special counsel to oversee the FBI’s Russian investigation; and an almost-daily wave of news reports have emerged that allege the president or his advisers tried to blunt or end the FBI’s investigation.

Trump has strongly denied the claims.

Rep. Devin Nunes, R-Calif., chairman of the committee, recused himself from the panel's Russia investigations after the House Committee on Ethics announced it was investigating Nunes for disclosing classified information.

Following Brennan’s public testimony before House lawmakers, he will hold a closed-door meeting to discuss the details.

At the public hearing, Brennan said Russians were actively rooting for Democratic candidate Hillary Clinton to lose and had a “more favorable view towards Mr. Trump.”

He said the animosity between Russian President Vladimir Putin and the Clintons went back years.