The FBI has information which suggests that associates of President Donald Trump worked with Russian operatives to coordinate the release of information that damaged Hillary Clinton's presidential campaign, CNN reports.
US intelligence officials say Russian President Vladimir Putin personally "ordered" a campaign of cyber attacks to hack Democratic Party institutions - and Clinton campaign staff - to influence November's election in Mr Trump's favour.
It's also now alleged the Trump campaign was involved in the timing of the release of emails.
CNN has spoken to US officials who say the FBI is reviewing "human intelligence, travel, business and phone records and accounts of in-person meetings".
The report comes days after FBI director James Comey confirmed the agency was investigating Mr Trump's campaign because of a "credible allegation of wrongdoing or reasonable basis to believe an American may be acting as an agent of a foreign power".
CNN quoted a law enforcement official as saying the information suggested "people connected to the campaign were in contact and it appeared they were giving the thumbs up to release information when it was ready".
However White House press secretary Sean Spicer has denied that any collusion took place between the Trump campaign and Russian operatives.
"Investigating it and having proof of it are two different things," he told reporters on Monday (local time).