Defence Secretary Philip Hammond said he was determined that the rules of engagement were followed in Afghanistan.
He told the BBC's Andrew Marr Show:
Everybody serving in theatre knows the rules of engagement, they carry cards in their uniforms with the rules on them in case they should need to remind themselves.
I can't comment on the specifics of this case.
We are very determined that rules of engagement will be followed, that any abuse will be dealt with through the normal processes of service justice and that is happening now.
Five Royal Marines have been charged with murder in relation to an alleged incident in Afghanistan in 2011.
Military police have arrested seven Royal Marines on suspicion of murder over an incident in Afghanistan, the Ministry of Defence has said.