FORT MEADE, Md. — Military prosecutors announced on Friday that they had decided to try Pfc. Bradley Manning on the most serious charges they have brought against him and seek a sentence that could be life without parole, despite his voluntary guilty plea to 10 lesser charges that carry a maximum total sentence of 20 years.

Private Manning admitted in court on Thursday that he had provided about 700,000 government documents to WikiLeaks, the antisecrecy group, in the most extensive leak of confidential and classified material in American history. But he pleaded guilty to the lesser charges in what is known as a “naked plea” — one made without the usual agreement with prosecutors to cap the potential sentence in return.

After the plea, prosecutors and their boss, the commanding general of the Washington Military District, had the option of settling for the 10 charges to which he had admitted his guilt and proceeding directly to sentencing. Instead, they said they would continue with plans for a court-martial beginning June 3, with 141 prosecution witnesses scheduled to testify.

“Given the scope of the alleged misconduct, the seriousness of the charged offenses, and the evidence and testimony available, the United States intends to proceed with the court-martial to prove Manning committed the charged offenses beyond the lesser charges to which he has already pled guilty,” said a statement from the military district.