Government cuts mean 5,000 posts will go this month and a further 9,500 over the next two years although some fear move could be rushed through to shorten the trauma, reports the Times.
Commanders however, have voiced fears that accepting voluntary rather than compulsory redundancies is leading to a loss of control over which posts lose manpower.
Crucial roles such as combat medics, linguists and interrogators are experiencing what the Army refers to as "gapping".
Jim Murphy MP, Labour’s shadow defence secretary, said: "The future shape of the Army is a critical national issue and any political row would signal an incompetence at the heart of government.
"There are now serious skills shortages in essential areas which could threaten our operational capability.
"We must be told if there is or will be an impact on operations in Afghanistan."
The government hopes that Territorial Army (TA) reservists can be used to fill the gaps, doubling the number available to 30,000.
General Sir Michael Rose, in a report from the UK National Defence Association (UKNDA), said over reliance on the TA "could prove fatal".
He wrote: "Given the past run-down of the TA including the closure of TA centres, the reduction in man training days and lack of funding for recruitment campaigns, it is clearly not possible to increase the trained manpower of the Reserves in time to compensate for regular soldiers being made redundant."
Speaking to the Guardian last week, US ambassador to Nato, Ivo Daalder, warned of the long-term consequences of military budget cuts.
He said: "If we don't start soon in investing in those capabilities then the gap between the US and the rest is going to grow. And if it is bad now, then it will be worse.
"If we have problems, they will be even worse."