CLASSIFIED British military documents have been found by a member of the public at a bus stop in England.

The papers, found in Kent, include an analysis of the tensions off the coast of Crimea last week.

They examine the likely Russian reaction to HMS Defender’s passage through Ukranian waters. Another set of documents discusses plan for a potential UK military presence in Afghanistan after the US-led Nato operation there ends.

The UK Government has launched a formal investigation, according to the BBC.

A Ministry of Defence spokesperson said an an employee had reported the loss of sensitive defence papers, adding: "It would be inappropriate to comment further.”

The 50-page dossier was found in a soggy heap behind a bus stop in Kent on Tuesday morning.

It includes emails and PowerPoint presentations, and is believe to have originated in the office of a senior official at the Ministry of Defence.

The papers, which have "Secret UK Eyes Only" marked on them, appear to show the possible routes for HMS Defender, with one route that would have kept HMS Defender away from disputed waters. More than 20 Russian aircraft and two coastguard ships shadowed the warship as it sailed near Crimea on Wednesday.

Boris Johnson insisted HMS Defender was “entirely right” to voyage through the disputed waters as Russia threatened to retaliate if there was a repeat of the incident.

Moscow claimed that warning shots were fired by Russian vessels at the destroyer – an assertion dismissed by the UK Government, which said only that a routine “gunnery exercise” took place.

The Prime Minister said the route was “wholly appropriate” and the destroyer was part of an international Carrier Strike Group that was “sticking up for our values”.

Addressing the press on Thursday following the incident, Johnson sidestepped a question on whether he had personally authorised HMS Defender’s voyage.

He said: “These are a matter for the MoD (Ministry of Defence) but if you want my view I think it was wholly appropriate to use international waters, and by the way the important point is that we don’t recognise the Russian annexation of Crimea, this is part of a sovereign Ukrainian territory, it was entirely right that we should indicate the law and pursue freedom of navigation in the way that we did, take the shortest route between two points, and that’s what we did.”