The officer allegedly did not furnish information about the status of his wife's permanent citizenship to the authorities, they said.
The sources said he was allegedly in touch with the woman for quite some time before marrying her and knew about her citizenship status.
The citizenship of the officer's wife was revealed after he applied for leave to go abroad to meet her, they said.
After the matter came to light, the officer was repatriated from NSG to his parent unit, which is deployed in Jammu and Kashmir.
"Under the Army act, officers have to seek permission from the service before contacting foreign nationals even if he subsequently wants to marry that person, otherwise they are liable to face action," military law expert col Rajiv Manglik said here.
Army personnel can be allowed to marry foreign nationals only if they leave the force or the spouse renounces his or her foreign citizenship.
A couple of years ago, the Bombay High Court had allowed a major to marry an American national and asked the Army to accept his retirement plea.