Foreign nationals who live abroad will be eligible to join the armed forces, as British residency requirements for service are set to be scrapped.
The Ministry of Defence will remove the need for Commonwealth citizens to have lived in the UK for five years before applying for service, ministers are set to announce on Monday.
The military hopes to recruit 1,350 extra personnel from overseas every year to the Navy, Army and Air Force.
It comes as the armed forces struggle to recruit enough servicemen and women to fill a shortfall in their ranks.
In April, a National Audit Office report said the full-time military was running at a 5.7% shortfall.
An extra 8,200 regulars and 2,400 engineers were needed to fill the "largest gap in a decade", the report added, while intelligence analysts and pilots were also in demand.
Applicants from nations including India, Australia, Canada and Fiji will be considered for all roles in the forces, without having lived in the UK.
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The army will begin the admissions from early next year, while the Navy and RAF will commence the process immediately.
Other than the Nepalese Gurkhas and applicants from the Republic of Ireland who can enrol under a special arrangement, those from outside the Commonwealth will still need British citizenship to apply.