Former CIA Director James Woolsey will no longer serve as a senior adviser to President-elect Donald Trump, Woolsey's spokesman said in a statement provided to reporters on Thursday.

"Effective immediately, Ambassador Woolsey is no longer a Senior Adviser to President-elect Trump or the transition," Woolsey's spokesman, Jonathan Franks, wrote in a statement that was first reported by CNN's Jeremy Diamond. "He wishes the President-elect and his Administration great success in their time in office."

Woolsey abruptly resigned from his position Thursday, one day before Trump was set to receive a conclusive briefing from US intelligence officials on Russia's role in the election-related hacks.

The Washington Post's Philip Rucker reported that Woolsey became uncomfortable after being cut out of intelligence talks with Trump and his national security adviser, retired Lt. Gen. Michael Flynn.

Woolsey came under scrutiny last week after implying to CNN's Jim Sciutto that Trump could be "playing us" with regard to what he knows about Russia's role in election-related hacks of Democratic Party organizations and officials.

"There's a possibility that he is, a little bit," Woolsey said, referring to Trump's statement at a New Year's Eve party at his Mar-a-Lago estate in Florida that he would reveal what he knew about the hacking campaign on "Tuesday or Wednesday" of this week.

"Why not?" Woolsey added. "He's not interfering with anything. He's not talking about anything classified ... This is a behavioral mode that he has perfected. He has a point, which is that it is entirely possible to have various definitions of hacking."

Woolsey also downplayed the intelligence report produced by his former agency that concluded that Russia was behind the hacking campaign on the Democratic National Committee and Hillary Clinton campaign chair John Podesta.

"We may see as time goes on an improved technology for sorting things out in the hacking world, but it is probably not always a good idea to say in these days and times that we know it was Russia, it was only Russia," he told CNN. "No, I'd be a little more cautious than that ... I think the Russians were in there, but it doesn't mean other people weren't."