The Ministry of Defence has lost track of military veterans they intend to recall at a time of national danger, according to a key government adviser.

About 95,000 former soldiers and officers are in the strategic reserve but it is claimed that officials have failed to maintain a full record of their contact details.

George Robertson, a former defence secretary and head of Nato who co-authored last year’s strategic defence review (SDR), made the claim at an event in Salisbury, Wiltshire.

“What the review talks about is having the strategic reserve, that is, all of the people in this room who’ve been in the forces who have got a continuing obligation,” the Labour peer said. “But the Ministry of Defence at the present moment doesn’t even know where most of them are. So we need to sort of round up those who are available and fit and willing to be able to do it.”

Under existing law, all former officers, regular and reserve, retain recall liability for life. The Ministry of Defence maintains contact with former military personnel in the first six years after they have left full-time service through an ‘annual reporting’ letter.

It is understood that records have not been similarly maintained for a larger cohort of personnel whose service ended more than six years ago and that the practice of maintaining contact with all veterans liable for recall fell by the wayside after the end of the cold war.

The SDR, chaired by Robertson, Gen Richard Barrons and Fiona Hill, a former chief adviser on Russia to the White House, recommended last June that the government should urgently address the issue of rejuvenating the strategic reserve.

Plans were proposed to map reservists’ locations and skillsets and to “make a more concerted effort to engage them under a refreshed veterans’ communications strategy”.

The government announced in January that as part of the armed forces bill they would increase the maximum age for military recall from 55 to 65.

The legal threshold for recall was also broadened to include ‘warlike operations’ rather than solely an ‘actual attack’ on the UK.

The strategic reserve is in addition to the active reserve that consists of an actively trained component of about 32,000 part-time and full-time volunteers.

But Robertson expressed his frustration this week that the government was still dragging its heels on committing fresh funding for the military and in preparing the country for war.

He accused Britain’s leaders of showing a “corrosive complacency” toward defence and putting the country “in peril” at a time when it was “under attack”. He said: “We are underprepared. We are underinsured. We are under attack. We are not safe … Britain’s national security and safety is in peril.”

The Royal United Services Institute has also criticised the scope and pace of the changes to the management of the strategic reserve. In a briefing paper published in February, the defence thinktank argued that the government had “not explained how recalled personnel would be funded for routine engagement, armed, trained collectively, or integrated with under-sized regular and reserve formations expected to generate corps-level effects or how they would integrate into homeland defence forces”.

Keir Starmer, the prime minister, recently echoed the warning of Nato that Russia would be ready to attack the alliance in three years.

An MoD spokesperson said: “We recognise the importance of the strategic reserve, which is why we are delivering on the Strategic Defence Review through our armed forces bill.

“The bill will expand our pool of reserves by increasing the maximum age limit for recall, enable seamless transfer between regular and reserve forces and give the defence secretary power to authorise recall for warlike operations. We are also constantly improving our data and communicating with our strategic reserve community to mobilise talent rapidly when it matters most.”