Washington (CNN) The FBI gathered intelligence last summer that suggests Russian operatives tried to use Trump advisers, including Carter Page, to infiltrate the Trump campaign, according to US officials.

The new information adds to the emerging picture of how the Russians tried to influence the 2016 election, not only through email hacks and propaganda but also by trying to infiltrate the Trump orbit. The intelligence led to an investigation into the coordination of Trump's campaign associates and the Russians.

These officials made clear they don't know whether Page was aware the Russians may have been using him. Because of the way Russian spy services operate, Page could have unknowingly talked with Russian agents.

Page disputes the idea he has ever collected intelligence for the Russians, saying he helped the US intelligence community. "My assumption throughout the last 26 years I've been going there has always been that any Russian person might share information with the Russian government ... as I have similarly done with the CIA, the FBI and other government agencies in the past."

But the intelligence suggests Russia tried to infiltrate the inner-workings of the Trump campaign by using backdoor channels to communicate with people in the Trump orbit, US officials say.

Page is one of several Trump advisers US and European intelligence found to be in contact with Russian officials and other Russians known to Western intelligence during the campaign, according to multiple US officials.

The scope and frequency of those contacts raised the interest of US intelligence agencies.

The FBI and CIA declined to comment on Page's statement.

In 2013, Page had meetings with a Russian man who turned out to be a spy, according to federal prosecutors. Page denied knowing that the man, Victor Podobnyy, was secretly a Russian operative living in New York.

As CNN first reported, Carter Page's speech critical of US policy against Russia in July 2016 at a prominent Moscow university drew the attention of the FBI and raised concerns he had been compromised by Russian intelligence, according to US officials. They also feared that Russian operatives maintained contact with him both in the United States and Russia, US officials say.

His conversations with suspected Russian operatives are being examined as part of a large intelligence-gathering operation by the FBI and other US agencies that was set up to probe Russia's interference in the election. The officials would not say what the conversations were about.

How Page's name became associated with the campaign is a reflection of how minimal the Trump operation was last year, as establishment national security figures avoided an association with the insurgent operation.

As Trump prepared to meet with The Washington Post editorial page in March 2016, the campaign was under pressure to name national security advisers. Staffers produced a list of names for Trump to refer to, according to a US official close to the campaign. Trump mentioned Page, in part because he had a Ph.D. listed next to his name, the official said.

Trump had never met Page. Sam Clovis, co-chairman of the campaign, helped gather the names that the candidate used.

Campaign officials say there's no indication Page ever attended any national security meetings at Trump Tower. They insisted he played a junior role and was not an influential figure.

But in a letter Page wrote to the House Intelligence committee offering to testify, Page describes more interactions with the campaign.

"For your information, I have frequently dined in Trump Grill, had lunch in Trump Cafe, had coffee meetings in the Starbucks at Trump Tower, attended events and spent many hours in campaign headquarters on the fifth floor last year."

A US official with close ties to the campaign says Page's claim he spent time on the fifth floor is meaningless since the campaign no longer used that floor starting in early July. The official also says the places he listed as visiting are public spaces visited by millions of people a year.

The FBI had Page on their radar for at least four years, according to court documents and US officials.

The bureau also knew about Page from its 2013 investigation into a Russian spy ring in New York. One of the spies was taped saying he tried to recruit Page, and Page admitted meeting him. But Page says he didn't share anything sensitive and didn't know he was talking to a spy.

He also traveled to Russia frequently and interacted with officials that the FBI was concerned were acting on behalf of the government.

His trip to Russia in July 2016 revived the FBI's interest, when he delivered a lecture at a graduation ceremony for the New Economic School. The university opened after the fall of the Soviet Union and is ranked as one of the best universities for economics in Russia. Former President Barack Obama gave a speech there during his first official trip to Russia in 2009.

But Page's lecture sounded different than what would be expected from most Americans. He parroted Kremlin talking points by chastising the West for prolonging "Cold War tendencies."

"Ironically, Washington and other Western capitals have impeded potential progress through their often hypocritical focus on democratization, inequality, corruption and regime change," he said, adding that US foreign policy toward Russia was "condescending" and "hostile."

Page stressed to the audience that he was there as a private citizen and not a Trump surrogate. But a spokesman for the school told CNN that Page's ties to Trump helped secure the invitation.

"The organizing committee for the commencement last year thought that he was a colorful and interesting character," said Denis Klimentov, a spokesman for the New Economic School. "It was partially supported by the fact that The Washington Post, the newspaper, back in the spring of 2016, cited Carter as one of Mr. Trump's foreign policy advisors."

Page maintains that he only met with "scholars and professors" during his July trip. Klimentov said that the New Economic School didn't arrange any meetings on Page's behalf.

"Physically and technically, frankly speaking, I don't think he had any time for that, he was with the school pretty much during most of the day, both days, and the remaining half of the day that he was in Moscow," Klimentov said.

But a former Obama administration official briefed on Russia's meddling in the election says Russians who work at prominent think tanks, universities and businesses often play an informal intelligence role.

"There are very few agencies of any kind that don't have some sort of intelligence or counterintelligence role," the official told CNN. "If you run an organization in Russia government, you will now have a role in that. It's the explicit mission of Russian government agencies."

Shortly after Page returned to the US, he and other Trump advisers headed to Cleveland for the Republican National Convention. On the sidelines of a convention-related event, Page and other Trump advisers, including JD Gordon and Jeff Sessions, met with Russian ambassador to the US Sergey Kislyak.

Two months after Page's trip, the FBI sought and received a warrant from the secret court that oversees the Foreign Intelligence Surveillance Act (FISA) to monitor Page's communications.

When he returned to Moscow in December 2016, after Trump won the election, Russian state-run media widely covered and promoted his trip, including RT and Sputnik, which have been identified by the US intelligence community as tools for the Kremlin's propaganda.

three RT published stories on all days of Page's trip. Sputnik published an 800-word roundup of the presentation and press conference he gave at the state-run news agency's headquarters. The RT affiliate Ruptly quickly published the full video of his second presentation and press conference.

That speech was given under the auspices of the Russian government: The event was held at the headquarters of the Rossiya Segodnya International Information Agency, a state-run media company created in 2013 by an official decree from Russian President Vladimir Putin.

Not only did Russian state-run media cover the trip, but a prominent government-run think tank involved in election-meddling efforts put out a press release heralding Page's visit.

The leader of the Russian Institute for Strategic Studie, Leonid Reshetnikov, painted Page as an influential adviser to Trump and said his visit could help improve US-Russian relations.

"It's quite possible that Trump's advisor is a pragmatist and a realist," Reshetnikov said, according to a translation of his comments in Russian. "This is probably not an ordinary visit. He has probably received some instructions from the President-elect. I don't think that meetings at the highest level will take place, but (the possibility) cannot be excluded."

Reuters reported this week that the group was involved in Russia's efforts to interfere in the US election. The organization sent recommendations to top Kremlin leaders with plans of how to use its propaganda machine to help Trump and undermine Democratic nominee Hillary Clinton.

The FBI and other US agencies have been combing through information obtained through that FISA as part of its ongoing investigation into the Trump campaign's links to Russia.

Intelligence analysts and FBI investigators who analyzed various strands of intelligence from human sources to electronic and financial records have found signs of possible collusion between the campaign and Russian officials. But there is not enough evidence to show that crimes were committed, US officials say.

Part of the problem for investigators has been that they lost their opportunity to conduct the investigation in secret after several leaks last year revealed FBI was looking at people close to the Trump campaign. After those reports, people that the US was monitoring changed their behavior, which made it more difficult for US officials to monitor them.

This story has been updated to reflect additional reporting on Page's role during the campaign.