Ministers face a grilling by MPs today on how documents containing details of a sensitive navy ship deployment in the Black Sea were found at a bus stop.
The Ministry of Defence has acknowledged that the loss of the documents was reported by an employee last week, after an anonymous member of the public told the BBC they found 50 pages of classified information in Kent.
Shadow defence secretary John Healey has been granted an urgent question in the Commons on Monday on the issue. He called the incident “as embarrassing as it is worrying for ministers.”
The papers included a set of documents that discussed the potential reaction of Russia to HMS Defender travelling through Ukrainian waters off the Crimea coast—a move that provoked a Russian military response.
Another document set out potential plans for a UK military footprint in Afghanistan.
HMS Defender is part of the carrier strike group bound for the Indo-Pacific on a mission touted by the government as symbolic of a long-awaited foreign policy pivot to the East, with a more wary eye on China.
The type 45 destroyer, however, temporarily peeled away from the carrier group to carry out its own mission in the Black Sea.
When the destroyer passed through international waters south of the Crimean Peninsula—annexed by Russia in 2014—it sparked a response from the Russian military.
Several Russian military aircraft shadowed the vessel, one at a height of 500 feet that defence secretary Ben Wallace said was “neither safe nor professional.”
The Russian military said it had fired what it described as warning shots from their vessels at the destroyer. This characterisation was rejected by the Ministry of Defence, which said that only a routine “gunnery exercise” took place.
Prime Minister Boris Johnson insisted the warship was “entirely right” to make the trip from Odessa in Ukraine to Georgia as an internationally recognised transit route.
The Ministry of Defence said that HMS Defender “conducted innocent passage through Ukrainian territorial waters in accordance with international law.” It said that “all potential factors” are considered when making “operational decisions.”
Moscow has threatened to retaliate if the incident is repeated.
A spokesperson for the MoD said: “The Ministry of Defence was informed last week of an incident in which sensitive defence papers were recovered by a member of the public. The department takes the security of information extremely seriously and an investigation has been launched. The employee concerned reported the loss at the time. It would be inappropriate to comment further.”
PA contributed to this report.