(ANSA) – Vatican City, October 2 – The Vatican on Tuesday opened an investigation into the detention conditions of Pope Benedict XVI's former butler Paolo Gabriele after he complained about the size of his prison cell. Gabriele is on trial at a Vatican court for allegedly stealing confidential Church papers. He told the court that he "couldn't even open his arms" in the first cell where he was detained following his arrest on May 23, adding that for the first 15-20 days the lights were always left on. "There was no light switch," Gabriele told the court. "The light was on 24 hours a day and this has also led to a reduction in my eyesight". He added that on the first night he was subjected to pressure and also denied a pillow. Vatican spokesman Father Federico Lombardi said afterwards that the probe had been opened to verify possible violations in Gabriele's treatment, but also to establish "whether there have been unfair accusations against the judicial authorities". Lombardi described the defendant's detention conditions as "very humane" and said that even the smaller cell in which he was originally detained "respected international standards". Meanwhile the Vatican Gendarmerie said in a statement that Gabriele had benefitted from "special attention" during his detention and that the light had been left on for security reasons and to prevent possible incidents of self-injury by the prisoner. The Vatican police corps also said that Gabriele could be liable to a counter-accusation should the charges turn out to be unfounded.