Seven marines were arrested on October 11 by the Royal Military police. Two more were later arrested, one on Friday and one yesterday. Four have been released without charge pending further inquiries, the Ministry of Defence said.
The marines were arrested on Friday after suspicious video footage was found on a serviceman's laptop by civilian police in the UK, the BBC reported.
The incident took place in Helmand province last year, but it is thought investigators only began an inquiry in recent weeks.
The charges are related to an incident in Afghanistan last year, when Royal Marine 3 Commando Brigade was based in Helmand, the report said.
An MoD spokesman said: "The Royal Military police has referred the cases of the remaining five Royal Marines to the independent Service Prosecuting Authority.
"Following direction from the SPA these marines have now been charged with murder and they remain in custody pending court proceedings.
"It would be inappropriate to comment further on this ongoing investigation," the spokesman added.
The Service Prosecuting Authority (SPA) is an independent body that conducts prosecutions on behalf of the military.
Bruce Houlder, the director of service prosecutions, will decide whether there is sufficient evidence to proceed to trial by court martial, which has similar powers to a crown court.
It is believed to be the first time UK servicemen have been arrested and charged with such charges during the Afghanistan conflict, the BBC reported.
The MoD previously said the incident followed an "engagement with an insurgent" and no civilians were involved.
Britain has some 9,500 troops in Afghanistan, all of whom are expected to leave by the end of 2014.
