The American soldier accused of providing more than 700,000 secret documents to the WikiLeaks website goes on trial in Maryland on Monday charged with the biggest leak of classified information in U.S. history.

Private First Class Bradley Manning, 25, faces a possible life sentence without parole if convicted for the 2010 leak that outraged the U.S. government.

Manning faces 21 counts, including the most serious one of aiding the enemy, as well as prosecution under the Espionage Act of 1917.

The court-martial at Fort Meade, Maryland, about 30 miles (50 km) northeast of Washington, is expected to run until at least late August. Prosecutors have said they expect to call more than 100 witnesses.

Manning pleaded guilty in court in February to 10 lesser charges that he was the source of the WikiLeaks release. He said he had released the files to spark a domestic debate on the military and on foreign policy in general.

Prosecutors rejected the pleas and are pursuing their original charges.

The judge, Colonel Denise Lind, said last month she would close parts of the trial to the public to protect classified material.

Manning, an intelligence analyst, was arrested in May 2010 while serving in Iraq. He was charged with downloading intelligence documents, diplomatic cables and combat videos and forwarding them to WikiLeaks, an anti-secrecy website.

WikiLeaks began exposing the secrets the same year, stunning diplomats and U.S. officials who said the leaks endangered lives.

WikiLeaks founder Julian Assange has taken refuge in the Ecuadorean Embassy in London since June 2012 to avoid extradition to Sweden for alleged sex crimes.

Civil liberties groups have argued that the court is restricting access to the case by withholding court documents and other information about proceedings from the public.

(Reuters)