Entire infantry and armoured units will face the axe as a result of the Government's programme of cuts to the armed forces, Defence Secretary Philip Hammond has warned.
In an interview with The Daily Telegraph he said the planned scale of reductions could not be achieved without the loss of some units.
Under the plans set out in the Strategic Defence and Security Review, the Army is to be reduced from 102,000 soldiers to 82,000.
The Telegraph reported that units with large numbers of soldiers recruited from the Commonwealth would be particularly vulnerable. Currently around one in 10 infantry soldiers comes from outside the UK, although some units have significantly larger foreign contingents than others.
"The Army is getting smaller," Mr Hammond said. "Clearly the Army can't get smaller by 17% without losing some units.
"I can't say to you that there will be no loss of battalions in the infantry as we downsize the Army. We are looking at the options in the Army and the armoured corps."
An MoD spokesman said: "A review of the future structure of the Army is ongoing and no conclusions have yet been reached.
"As General Sir David Richards, Chief of the Defence Staff, has stated previously, the Army is confident it can meet its target of 82,000 by 2020.
"This is in line with the agreement between the Defence Secretary and the Chief of the General Staff for a gradual move towards the new Army structure so operations are not adversely affected by necessary changes."