Russian operatives sought to infiltrate the Trump campaign using some of the US president’s own advisers, including Carter Page, according to a CNN report that cited unnamed US officials.

Page, a former Merrill Lynch banker who Trump referred to as a foreign policy adviser during his presidential race, has emerged as a key figure in several US investigations into possible coordination between the Kremlin.

New allegations that federal investigators have gathered intelligence that suggests Russian operatives may have used Page to try to gain access to the Trump campaign follows a separate report by the Washington Post that he was being monitored by the FBI last summer because of suspicions about his ties with Russia.

Page has denied wrongdoing. He acknowledges that he might have shared information with Russians but has insisted that the information was innocuous.

“Nothing I was ever asked to do or no information I was ever asked for is anything beyond you could find on CNN,” Page told the media network on Saturday. “Nothing I ever talked about with any Russian official extends beyond that – publicly available, immaterial information.”

He also told CNN that he had shared information with “the CIA, the FBI and other government agencies in the past”.

Contacted by the Guardian, Page declined to elaborate on reports that he had previously been in contact with US intelligence agencies and investigators.

By his own admission, the former adviser met top Russian officials at Rosneft, the Russian state oil firm, as late as last December, shortly before the company announced it was selling a 19.5% stake to Glencore, among other investors.

Page told Russian media at the time that he had the “opportunity to meet with some of the top managers of Rosneft”. He also suggested that the deal, which involved an investment by a Qatar fund, was a good example of how US companies were being kept from pursuing opportunities because of US sanctions against Russia. He denied meeting Rosneft’s chief, Igor Sechin, whom he referred to as “Igor Ivanovich” in one interview.

Among other areas congressional investigators are examining are questions about whether former Trump campaign officials discussed lifting US sanctions in meetings with Russian operatives.

The Guardian reported last week that questions about Page’s views about Russia date back nearly two decades, when he briefly worked at the Eurasia Group, a prominent advisory firm. Ian Bremmer, the president of Eurasia, said Page’s “pro-Kremlin” views were not clear at the time he was interviewed and that it was subsequently determined that he “wasn’t a good fit” at the firm.

In a text on Saturday, Page called the allegation “complete nonsense”.

US officials told CNN that it was still unclear whether Page knew that Russian operatives were using him to gain a foothold into the Trump campaign and that he may have unwittingly been talking to Russian agents.

It is not the first time Page is alleged to have been in contact with Russian operatives. A January 2015 indictment of a Russian spy ring identified Page, under a pseudonym, as a contact of a Russian intelligence operative, Victor Podobnyy. Page confirmed to BuzzFeed that he was Podobnyy’s “Male #1” associate, from whom Podobnyy, operating out of Russia’s UN office, acquired documents about the US energy industry.

“I think he is an idiot and forgot who I am ... He got hooked on Gazprom thinking that if they have a project, he could rise up,” court papers quote Podobnyy as saying about Page.