Defence cuts mean British military commanders will have to rely on private security firms to carry out future operations, a retired general has said.
Major General Graham Binns said the UK's Ministry of Defence appeared more "reticent" about using armed contractors to support missions than other countries and other Whitehall departments.
He called on the Government to introduce a system for selecting and vetting a number of approved private security companies, which would be required to train regularly with troops.
Maj Gen Binns, who commanded coalition forces in southern Iraq from mid-2007 to early 2008, is chief executive of British private security company Aegis Defence Services.
Writing in a book of essays published by the Army about how it should adapt for the future, he suggested that private security contractors (PSCs) would become an integral part of the forces deployed on operations.
"Given the current economic climate and future force structures, it is likely that commanders of future military operations of whatever type will encounter PSCs," he said.
"Given the current size and structure of UK forces, it is inevitable that any future expeditionary deployment will require contractor support in many areas.
"PSCs may well come to feature as part of the force structure as there are many combat-support functions that can be fulfilled by PSCs, thus releasing troops for other duties."
The former general's comments come as the MoD is implementing a programme which could see 11,000 redundancies across the Royal Navy, Army and RAF by April 2015 in an effort to tackle the deficit and bring the defence budget under control.
Maj Gen Binns said British security firms had provided services for the US Army in Iraq and Afghanistan ranging from gathering local intelligence to guarding senior officers.
He wrote: "The MoD could certainly afford to rely more on PSCs ... yet there appears to be a reticence in defence to the use of armed contractors in support of operations.
"This reticence is not replicated by the other Government departments and certain other nations."
He added: "Given the likely shape of future operations, there will be an ever greater requirement to support both regular and reserve forces on operations with contractors, including PSCs.
"It would be prudent to recognise this and prepare for it at an early stage."
But the retired general also warned that private security firms not working directly with the military could be "more problematic", noting that they could include "rogue" companies hiding behind the veil of a legitimate contractor or "thinly disguised local militias".