The documents also included sensitive political and military information on Nato and EU activity in Afghanistan and Georgia, reports the AFP news agency.

BBC: Russian spy Raymond Poeteray jailed by Dutch

The infiltration is further evidence the spying focused on economic secrets as well as military and political information.

WSJ: Russian Spy Ring Aimed to Make Children Agents

But even "legal mail, " according to the rules mandated by Judge Joyce Hens Green in a 2004 protective order, prohibits lawyers from giving detainees information relating to military operations, intelligence, arrests, political news and current events, and the names of U.S. government personnel.

CENTERFORSECURITYPOLICY: Gitmo��s indefensible lawyers