Six British Army soldiers have been arrested over an alleged sexual assault.
It is understood defence secretary Gavin Williamson is "appalled" by the claims and is launching a review of behaviour across the military.
According to the Sun, the alleged attack was against a teenage female soldier.
Mr Williamson said: "There is no place for these kind of actions in the military and, if true, those involved must face the full force of the law."
Chief of the General Staff, General Sir Mark Carleton-Smith, said inappropriate behaviour was "downright unacceptable".
"It stands in stark contrast with everything the British Army represents, demonstrating an indiscipline that is wildly at odds with the values and standards that represent the fabric of not just our Army, but the nation's Army," he said.
It comes after the Army faced criticism this week when a video emerged showing soldiers using a picture of Jeremy Corbyn for target practice.
The Ministry of Defence launched an investigation into the conduct of the personnel from 3rd Battalion, Parachute Regiment, who were filmed in Kabul, Afghanistan, shooting at a picture of the Labour leader.