A shortage of spares for Royal Navy warships and submarines has forced the Ministry of Defence (MoD) to remove parts from other ships, the National Audit Office has revealed.
An NAO investigation found equipment "cannibalisation" had increased by 49% over the past five years.
The organisation warned that the practice was costing the MOD millions and would ultimately delay construction.
However, the MoD responded by saying components were only swapped when "absolutely necessary".
The Royal Navy’s current fleet currently has 19 frigates and destroyers and seven attack submarines.
Unfortunately, a shortage of necessary parts occasionally prevents them from going to sea.
The NAO said that the construction of new Astute class submarine HMS Artful had been delayed by 42 days due to parts being “borrowed” during its construction.
This also reportedly added nearly 5m to the cost of building the ship.
Forces News analysed the report and spoke to former First Sea Lord Admiral Lord West:
It was also revealed that last year alone there were 795 instances of spare parts being borrowed from other vessels.
Between 2012 and 2017, there were 3,230 instances overall.
The report noted that in some circumstances, for example during high-intensity operations, this might be the best way to ensure vessels remain at sea.
However, the NAO also said that such practice increased costs, and that it had led “to an estimated £40m cost increase”.
The report added: "In the past two years, the Navy has removed an estimated £92m from its maritime support in-year budgets."
A Royal Navy spokesperson said:
"Less than 0.5% of parts we use come from swapping components, and we only do this when it's absolutely necessary to get ships out of port and back on to operations more quickly.
"We continue to make improvements to how we manage this long-established practice."