By Tom Ramstack

FORT MEADE, Maryland (Reuters) - The military judge who last week convicted soldier Bradley Manning of committing the biggest breach of classified data in U.S. history through WikiLeaks on Tuesday trimmed the maximum prison sentence the private first class could face.

But the 25-year-old former intelligence analyst could still be spending the rest of his life behind bars after Judge Colonel Denise Lind ruled that he could face a maximum sentence of 90, rather than 136, years for turning over more than 700,000 battlefield videos, diplomatic cables and other secret documents to WikiLeaks.

Manning's attorneys had objected that the prosecution was overreaching in seeking separate sentences for all the espionage charges. His lawyers acknowledged he had downloaded files on different days, but said he grouped many of them into single files before transmitting them in 2010 to WikiLeaks, a pro-transparency website.

Lind, who convicted Manning of 19 criminal counts, ruled that some counts resulted from the same sequence of actions by Manning and should be merged to avoid "an unreasonable multiplication of charges."

For most of the espionage charges resulting from the transmissions, "there is no evidence of prosecutorial overreaching," Lind said.

The court-martial of the slightly built soldier, who was working as an analyst in Iraq when he released the documents to the anti-secrecy site, has drawn international scrutiny. The trove of documents he provided catapulted WikiLeaks and its founder, Julian Assange, into the spotlight.

The U.S. government contended that releasing classified information threatened national security.

Access to classified information remains a sensitive subject after Edward Snowden, a U.S. intelligence contractor, this summer revealed the super-secret National Security Agency program to collect phone and Internet records.

Manning, a low-level intelligence analyst described during the trial as an Internet expert, faces the prospect of decades of prison monotony without online access, likely at the U.S. Disciplinary Barracks at Fort Leavenworth, Kansas.

MISTREATMENT

The sentencing phase of Manning's court-martial began last week and is expected to last at least until Friday. Lind ruled during preliminary hearings that the sentence would be trimmed by 112 days because Manning was mistreated following his arrest in Iraq in May 2010.

Manning last week was found not guilty of the most serious charge of aiding the enemy, which carried the threat of life in prison without parole, and his lawyers have portrayed him as naive but well intentioned. They argue his aim was to provoke a broader debate on U.S. military policy, not to harm anyone.

In an interview on CNN, his father Brian Manning said he was "relieved" his son was not convicted of aiding the enemy but said: "It's upsetting and frightening that your son is being accused of these horrible breaches of security."

The elder Manning said he believed his son was innocent but that the two have not spoken in months, at his son's request.

"I still love my son," he said in the interview.

After Lind's ruling, two military officials - Major General Michael Nagata, the deputy chief for the Office of the Defense Representative to Pakistan from 2009 to 2011, and Air Force Colonel Julian Chesnutt, a U.S. military adviser at the U.S. Embassy in Pakistan from 2010 to 2012 - testified behind closed doors on the impact of the WikiLeaks releases on relations with Islamabad.

Lind also ruled she would not allow the prosecution's "aggravation evidence" to be considered in sentencing unless it could be shown to be "a direct and immediate result" of information he gave to WikiLeaks. Aggravation evidence refers to problems that worsened because of a criminal offense.

In a sign of the international furor the Manning case has generated, a play about the gay soldier won a newly created drama prize on Tuesday at Britain's oldest literary awards.

(Editing by Ian Simpson, Chris Reese, Bernard Orr and Lisa Shumaker)