The trial of Pope Benedict XVI's former aide, Paolo Gabriele, opened on Saturday in a 19th century courtroom behind the apse of St Peter's basilica which is normally off-limits to the public within the small Vatican city-state.

Gabriele did not speak at the trial opening, but is expected to testify next Tuesday. Television cameras were largely excluded from the courtroom and only eight journalists were allowed to observe proceedings throughout. They later briefed other journalists.

The court comprising three Italian law professors ruled that only evidence provided by a Vatican prosecutor and Vatican police would be admissible. The court declared that the results of a separate probe carried out by cardinals was not admissible.

Presiding judge Giuseppe Dalla Torre, said the trial might be wrapped up in four court hearing days. Attendees in the public gallery included Vatican spokesman Federico Lombardi.

Separate trial for another accused

The court also accepted a request for the trial of Claudio Sciarpelletti -- a Vatican computer technician who is accused of abetting Gabriele's crime -- to be conducted separately. No date for that hearing was set.

Gabriele, a once loyal papal assistant, had been quoted by prosecutors - when arrested last August - as describing himself as a whistle-blower, who was trying to expose alleged graft at the headquarters of the Roman Catholic Church.

Gabriele faces a charge of aggravated theft, and, if convicted by the panel, the 46-year-old could face a prison sentence of up to four years.

Prosecutors had alleged that Gabriele met with investigative reporter Gianluigi Nuzzi earlier this year and gave him copies of the documents which were then widely published across international media outlets.

Power struggle exposed

The allegedly leaked documents pointed to a power struggle at the highest level of the church and offered insight into the workings of the Holy See.

A spokesperson for the Vatican said the 85-year-old pontiff was hurt by the betrayal of confidence by someone he "knew, loved and respected."

The papal state has no prison system, meaning if convicted, Gabriele would serve time in an Italian jail, however, it is expected the pope will pardon him.

ipj/dr (AFP, Reuters, dpa, AP)