(CNN) -- Formal charges are expected against seven Royal Marines who were arrested this week on suspicion of murder involving an incident in Afghanistan in 2011, a British Ministry of Defense spokesman said.
The arrests were made after an incident in Helmand province, the spokesman said.
All seven are in the UK and will proceed through a military court system that mirrors the civilian legal system.
The incident occurred after an engagement with an insurgent, and no civilians were involved, the spokesman said.
Those arrested were part of Operation Herrick 14, as Britain's efforts in Afghanistan are known. The operation they were carrying out at the time did not involve any special forces, the spokesman said.
"The investigation will now be taken forward and dealt with by the Service Justice system," the spokesman said. "These arrests demonstrate the Department and the Armed Forces' determination to ensure UK personnel act in accordance with their Rules of Engagement and our standards."
The military will review the serious incident to identify lessons learned, the spokesman said.