CNN has reviewed a 35-page compilation of the memos, from which the two-page synopsis was drawn, but said it is not reporting their details as it has not independently corroborated the specific allegations.
It is claimed some of the memos were circulating last summer but US intelligence agencies have now checked out the former British intelligence operative and find him and his sources to be credible enough to present the information.
They were prepared by the former MI6 agent, who was posted in Russia in the 1990s and now runs a private intelligence gathering firm.
CNN claim his investigations on Trump were initially funded by groups and donors supporting Republican opponents during the GOP primaries and further investigation was funded by groups and donors supporting Hillary Clinton when he became a nominee.
Spokespeople for the FBI and the Director of National Intelligence have declined to comment.