Donald Trump's former adviser claimed British academics deliberately failed his PhD thesis twice because they were "anti-Russian", it has emerged.

Carter Page, who was Mr Trump's foreign policy adviser before the presidential election, took three attempts to gain his doctorate from a London university.

British examiners took the unusual step of failing his PhD not once, but twice, calling it "verbose" and "vague".

But Mr Page, who joined the Trump campaign in early 2016, blamed two respected academics, Professor Gregory Andrusz, and Dr Peter Duncan, for his failed attempts.

Mr Page compared his difficulties in earning the qualification to the ordeal suffered by Mikhail Khodorkovsky, an exiled Russian businessman who spent a decade in a Siberian prison on the orders of Vladimir Putin.

In emails seen by the Guardian newspaper, Mr Page told the academics: “Your actions to date have been far more destructive than anything I have personally experienced in my 39 years on this planet.”

He added that Mr Khodorkovsky's suffering represented “the closest analogy in recent history to my trials”.

Mr Page first submitted his thesis on central Asia’s transition from communism to capitalism in 2008 before attending a face-to-face interview on his research with the examiners.