The Federal Bureau of Investigation (FBI) reportedly has information in its possession that suggests Trump campaign associates were in contact with Russian operatives.

Campaign associates are said to have worked with Russian connections to release information damaging to former Democratic presidential candidate Hillary Clinton, according to US officials cited by CNN.

The agency is now in the process of reviewing the information, which includes human intelligence, business, travel and phone records and in-person meeting accounts.

Based on the information, the FBI counter intelligence investigators suspect that people working in the Trump campaign might have coordinated with Russia. However, officials cautioned that the information is not conclusive and the investigation is still underway.

The FBI as well as the White House have declined to comment on the CNN report.

One official said, "people connected to the campaign were in contact and it appeared they were giving the thumbs up to release information when it was ready", while other officials said that it was too early to draw that conclusion and from the information collected so far because it is circumstantial.

The collusion cannot yet be proved by the FBI. According to a source cited by CNN, the agency is now facing a hurdle in finding conclusive intelligence as contacts between the associates and Russians have completely ground to halt in recent times.

The investigators are still reviewing and analysing the information and are looking for any indications of a potential cooperation, US officials said.

Four former Trump campaign associates – Carter Page, Paul Manafort, Roger Stone and Michael Flynn are already under FBI investigation for communication with Russians known to the US intelliegence agencies. All four have denied contacts with Russia.

A string of alleged links between Trump and Russia have emerged Reuters/Lucas Jackson