The Department of Defense said an agent told him last week that the documents had been lost and an investigation had been opened.
“It shouldn’t be able to happen,” Minister for Northern Ireland Brandon Lewis told Sky News on Sunday.
“It was reported correctly at the time … there is an internal investigation into this situation.”
An anonymous citizen told the BBC that he found 50 pages of classified information behind a bus stop in Kent, southern England, on Tuesday.
The newspapers discussed the possible Russian response to the British HMS Defender, which was traveling through Ukrainian waters off the coast of Crimea on Wednesday, the BBC reported.
Russia said Wednesday it fired warning shots at the naval destroyer in the Black Sea after violating its territorial waters.
However, the UK said it was making “innocent passage through Ukrainian territorial waters in accordance with international law”.
The incident occurred off the coast of Cape Fiolent in Crimea, which Russia annexed from Ukraine in 2014, which the vast majority of the international community has not recognized, according to Moscow.
The documents appear to indicate that British officials knew the route could lead to a possible reaction from the Russians, but that an alternate passage from Moscow could be viewed as “the UK scared / running away”.
Instead, the path taken would offer “an opportunity to get in touch with the Ukrainian government … in the waters recognized by Great Britain as Ukrainian territorial waters,” according to another document.
The Russian Foreign Ministry called the British ambassador to a “strong protest” against the incident on Thursday.
Kremlin spokesman Dmitry Peskov called it a “deliberate and prepared provocation”.
The Russian Defense Ministry announced that warning shots were fired and bombs dropped on the way of the HMS Defender.
Documents were found at the bus stop that set out plans for a possible British military presence in Afghanistan after the end of NATO operations there.