By Dave Warner

PHILADELPHIA (Reuters) - The jury in the child sex abuse trial of a Philadelphia Roman Catholic monsignor ended an 11th day of deliberations on Tuesday without reaching a verdict in the case of the most senior U.S. clergyman to stand trial in the church's wide-ranging pedophilia scandal.

Monsignor William Lynn, 61, is accused of conspiracy and child endangerment. Prosecutors say that in his job overseeing hundreds of priests in the Philadelphia Archdiocese, Lynn covered up child sex abuse allegations, often by transferring priests to unsuspecting parishes.

Also on trial is the Reverend James Brennan, accused of child endangerment and attempted rape of a 14-year-old in 1996.

The Common Pleas Court jury heard 10 weeks of testimony and began deliberating on June 1. After concluding their 11th day of deliberating, the jurors went home and were scheduled to resume at 9:30 a.m. on Wednesday.

At the end of the jury's day, Judge M. Teresa Sarmina took the unusual step of calling the seven prosecutors and defense attorneys present in the courtroom into her chambers for a brief closed-door meeting.

They emerged from the meeting grim-faced but were not allowed to comment on what transpired due to a judge-imposed gag order in the case.

As the days of deliberation have worn on, jurors too have been looking more somber. One defense attorney has said they appear to be "struggling."

If convicted, Lynn faces the possibility of 21 years in prison. Prosecutors say his motive was to avoid scandal and any potential loss of donations to the archdiocese, the nation's largest with 1.5 million members.

Lynn supervised 800 priests in the Philadelphia Archdiocese, and was responsible for investigating claims of sexual abuse, between 1992 to 2004.

The defense said Lynn tried to handle documented cases of pedophile priests, making a list in 1994 of 35 accused predators and writing memos to suggest treatment and suspensions.

It said Lynn was hampered because he could only make recommendations to the head of the archdiocese, Cardinal Anthony Bevilacqua, who died in January at age 88.

(Editing By Ellen Wulfhorst, Cynthia Johnston and Todd Eastham)