Former Trump campaign foreign policy adviser Carter Page said he was a source for several agencies in the U.S. government for years before he became the subject of the federal investigation into Russian interference in the 2016 election.

Working as an American consultant with Russia expertise, he told Fox News that over the years he spoke with the State Department, FBI, and the CIA.

"I was asked various questions, not only by State, FBI, et cetera, but also CIA," he said on "Sunday Morning Futures." "I had a long-standing relationship with the CIA going back decades essentially, and I was always very transparent, open."

Soon after he left the Trump campaign, Page became the subject of Foreign Intelligence Surveillance Act warrants beginning in October 2016, which relied on British ex-spy Christopher Steele's dossier packed with unverified claims about President Trump's ties to Russia. Steele was hired by the opposition research firm Fusion GPS, which was itself being paid by the Hillary Clinton campaign and the Democratic National Committee through the Perkins Coie law firm. The fact that the dossier had Democratic funding was not revealed to the Foreign Intelligence Surveillance Court.

Page was also a subject of special counsel Robert Mueller's investigation into Russian interference in the 2016 campaign. Although Mueller determined Russia meddled in election affairs, he did not accuse Page of coordinating with Russian agents and did not establish criminal conspiracy between the campaign and the Kremlin.

Page has been heavily critical of the Russia investigation and the media coverage of it, which he claimed was an effort to advance a narrative for impeachment.

"Unfortunately, it was completely spun that as you're correctly alluding to in this fake Mueller report, they just refer to this as oh, he's, you know, colluding, if you will, with these Russian intelligence officers," he said. "I mean, I'm acting as a source, completely helping our government."

"Oh, by the way, doing it for free," Page said, noting that this stands in stark contrast to conservative watchdog Judicial Watch's findings that the FBI made 11 payments to Steele in 2016 and the Democrats' ties to Russian oligarchs.

"So unethical," he said.