A figure in Donald Trump’s election campaign was so concerned about Russian links that they approached the FBI before the vote, it has been claimed.

The source passed on information that confirmed details in a dossier of lurid claims about Mr Trump compiled by a former British spy, according to a leaked transcript.

The claim was made by Glenn Simpson, the founder of the company which financed the dossier, during a behind-closed-doors interview with a congressional committee.

Mr Simpson declined to name who the Trump source was, citing “security” and warning that “people who get in the way of the Russians tend to get hurt”.

However he indicated that the figure came forward voluntarily because they had “concerns” about national security.