The former M16 spy behind the dossier which linked Donald Trump and Russian collusion has broken his 18-month silence by taking a swipe at the US President.

Christopher Steele, in an email to the editor of Vanity Fair, said it was "hard to speak unpalatable truths to power" and appeared to level criticism at Vladimir Putin.

The content of the email has been seen by Sky News, and is reported to say: "I find myself in the company of many talented and distinguished people, although I personally would not accord such accolades to some of the other foreign nationals included in the list.

"In these strange and troubling times, it is hard to speak unpalatable truths to power, but I believe we all still have a duty to do so.

"I salute those on your list, and otherwise, who have had the courage to speak out over the last year, often at great personal cost.

"At a time when governance is so distorted and one-sided, as I believe it currently is in the United States, the media has a key role to play in holding it accountable."

Mr Steele’s dossier included claims that Mr Trump paid prostitutes to perform obscene sex acts during a visit to Russia - an unsubstantiated allegation that he has always vehemently denied.