Donald Trump. Drew Angerer/Getty Images The US intelligence community has opened investigations into several members of President Donald Trump's inner circle over the past year, focusing on the advisers' potential ties to Russian government officials throughout Trump's presidential campaign and beyond.

The investigations appear to have begun as early as last spring, when the CIA established a US counterintelligence task force to investigate whether the Trump campaign received funds from Russia. The task force consisted of the FBI, the Treasury and Justice departments, the Office of the Director of National Intelligence, and the National Security Agency.

The BBC first reported on the existence of the investigation earlier this month, which McClatchy also reported was still ongoing. The investigation sought, among other things, to determine who financed the hacks on the Democratic National Committee and of Hillary Clinton's campaign chairman, John Podesta, and whether any of Trump's associates served as middlemen between his campaign and the Kremlin.

John Brennan, the former director of the CIA, also received a recording of a conversation last year from one of the Baltic states' intelligence agencies suggesting that money from the Kremlin had gone to the Trump campaign, the BBC reported.

One night before Trump's inauguration, The New York Times reported that intercepted communications were part of the investigation into ties between Russia and people close to Trump, but the report said it was "not clear whether the intercepted communications had anything to do with Mr. Trump's campaign, or Mr. Trump himself."

The BBC report indicated that the task force was granted a warrant by a judge in the FISA court — named after the Foreign Intelligence Surveillance Act — on October 15 to intercept the electronic records from two Russian banks that could have been implicated in any money transfer. Trump was not named in the warrant, but three of his associates were the subject of the inquiry.

All three associates contacted, but not named, by the BBC, denied the allegations contained in the report.

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Trump's potential ties to Russia have come under increased scrutiny amid allegations contained in a 35-page dossier from a former British intelligence officer. The unverified claims contained in the dossier include that his campaign colluded with the Kremlin during the election to undermine Hillary Clinton.

Paul Manafort, Trump's one-time campaign manager who served as a top adviser to a pro-Russian political party in Ukraine from 2004 to 2012, emerged as a central figure in both the dossier and the intelligence community's early inquiries into Trump's ties to Russia.

Secret ledgers uncovered by an anticorruption center in Kiev and obtained by The New York Times revealed that former Ukrainian President Victor Yanukovych's political party, the pro-Russia Party of Regions, earmarked $12.7 million in undisclosed cash payments to Manafort for his work from 2007 to 2012.

Manafort has denied ever having collected the earmarked payments. But the unverified dossier on which top US leaders have been briefed alleges that Yanukovych "confided directly to Putin that he authorized kickback payments to Manafort," who "had been commercially active in Ukraine right up to the time (in March 2016) when he joined campaign team."

Paul Manafort. Chip Somodevilla/Getty Images

The dossier also alleged that Manafort, who resigned as Trump's campaign manager on August 19, served as a liaison between Trump's campaign team and Russian government officials. The FBI looked into Manafort last year for ties to Russian officials and business interests that Manafort has said do not exist.

"I have never had any relationship with the Russian [government] or any Russian officials," Manafort told The Wall Street Journal. "I was never in contact with anyone, or directed anyone to be in contact with anyone."

Two other Trump allies, Carter Page and Roger Stone, have also been scrutinized by the intelligence community for their relationships with Moscow. Page served as an early foreign-policy adviser to Trump, and Stone advised Trump's campaign until August 2015.

Page's extensive business ties to state-owned Russian companies, stemming from his time as an investment banker in Moscow in the early 2000s, were investigated by the FBI last summer. The bureau also looked into Stone's ties to WikiLeaks, which published the hacked Podesta emails last year.

Roger Stone. Business Insider

On Sunday, The Wall Street Journal reported that Trump's national security adviser, Michael Flynn, was being investigated by counterintelligence agents over his phone calls to Russia's ambassador to the US, Sergey Kislyak, on December 29. That was the day that President Barack Obama sanctioned Russia over its election-related hacking and expelled 35 Russian diplomats from the US.

Sean Spicer, the new White House press secretary, said at the time that Flynn's calls to Kislyak "centered around the logistics of setting up a call with the president of Russia and the president-elect after he was sworn in."

But CNN reported on Monday that the calls, "captured by routine US eavesdropping targeting the Russian diplomats," raised "enough potential concerns that investigators are still looking into the discussions amid a broader concern about Russian intelligence-gathering activities in the United States."

Flynn's ties to Russia were scrutinized after he attended a gala in Moscow in 2015 celebrating the 10th anniversary of the state-sponsored news agency Russia Today. Flynn was photographed sitting next to Russian President Vladimir Putin at the gala's dinner.