Garry Graham, Prospect's deputy general secretary, responding to the PAC report showing a £7bn funding blackhole, said:
Behind the huge gap in defence funding are real jobs and skills in the UK defence sector that are in real danger of being lost forever if this is not urgently addressed.
"We have already seen significant lay-offs over the past year as a result of uncertainty and delays on future funding.
"Scientists, engineers and specialists in both the public and the private sectors deserve much better than the huge funding uncertainty that they have.
"Whether in defence manufacturing, or in operations and maintenance, it is vital to the UK’s national security that we maintain this sovereign capability.
"Rather than chasing huge efficiencies which no longer exist, the Treasury must address this with the extra money that our defence so urgently needs."