The most serious of the new charges is "aiding the enemy," a capital offense which carries a potential death sentence.
According to the officials, the U.S. military rounded up many of those named and brought them into their bases for protection. But, according to one military official, "We didn't get them all." Military officials tell NBC News a small number of them still have not been found.
Manning's lawyer, David Coombs, did not immediately return a call from msnbc.com for comment.
But Coombs wrote on his blog Wednesday that it was uncertain whether any additional charges filed against his client would stick.
"The decision to prefer charges is an individual one by PFC Manning's commander," he wrote. "The nature of the charges and the number of specifications under each reflects his determination, in consultation with his Staff Judge Advocate's office, of the possible offenses in this case. Ultimately, the Article 32 Investigating Officer will determine which, if any, of these additional charges and specifications should be referred to a court-martial.”
Manning, 23, was first charged on July 6, 2010, with illegally downloading and transferring defense information to an "unauthorized source," when he worked as a military intelligence analyst in Baghdad. He was also charged on accusations that he obtained 150,000 classified State Department cables, many of which were also eventually released by WikiLeaks.