Robert Mueller, the special counsel investigating links between Donald Trump’s campaign and Russia, has detailed how the FBI missed a chance to question a London-based professor caught up in the inquiry.

Prosecutors working for Mr Mueller filed court documents recommending a jail sentence for George Papadopoulos, a former Trump campaign foreign policy adviser.

Mr Papadopoulos has admitted lying to the FBI about his contacts with Professor Joseph Mifsud.

The professor is alleged to have told Mr Papdopoulos that the Russians possessed "dirt" on Hillary Clinton in the form of emails, before those emails became public. Prof Mifsud, who is Maltese, has denied doing so.

The Mueller court documents said Mr Papadopoulos caused irreparable damage to the Russia investigation because he lied repeatedly to agents during a January 2017 interview.

Those lies, prosecutors said, resulted in the FBI missing an opportunity to properly question Prof Mifsud.

It was suggested in the documents that the FBI had contact with Prof Mifsud while he was in the US during the early part of the investigation.

FBI agents"located" him in Washington about two weeks after Mr Papadopoulos’ January 2017 interview.

But Mr Papadopoulos’ lies "substantially hindered investigators’ ability to effectively question" the professor.

The court filing said: "The defendant’s lies undermined investigators’ ability to challenge the professor or potentially detain or arrest him while he was still in the United States."

It noted that the professor left the US in February 2017 and has not returned since.

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The documents said: "Had the defendant told the FBI the truth when he was interviewed in January 2017, the FBI could have quickly taken numerous investigative steps to help determine, for example, how and where the professor obtained the information, why the professor provided the information to the defendant, and what the defendant did with the information after receiving it."

Prof Mifsud was previously honorary director of the London Academy of Diplomacy, which is affiliated to the University of Stirling in Scotland. It was not clear if he still holds that role.

In October he told The Telegraph he had known nothing about emails containing "dirt" on Mrs Clinton, and that he had a "clear conscience".

The professor said he was “upset" by the claims because they were "incredible".