ROME (Reuters) - The Vatican, at the start of a conference on protecting children from online sexual abuse, pledged on Tuesday to seek the truth about one of its diplomats whom it recalled after he became suspected of possessing child pornography.  This is a very painful episode and a great trial for all involved,  said Cardinal Pietro Parolin, the Vatican s Secretary of State and number two in the Holy See. Parolin was referring to the case of a monsignor who was recalled to the Holy See from its Washington embassy in August after the U.S. State Department said he may have violated child pornography laws.  We are treating the case with the maximum seriousness, the maximum commitment and the maximum attention,  Parolin told reporters as he arrived to deliver the conference s keynote address. He said the case was under judicial secrecy  to protect the investigation and to protect truth and justice . The Vatican never identified the monsignor, who is also wanted in Canada on suspicion of uploading child pornography from a social networking website in 2016. He is being investigated by Vatican prosecutors and will stand trial in the Vatican if indicted.   In his keynote speech, Parolin said the Catholic Church wanted to  share the experience  it had acquired from dealing with its own scandals concerning priestly sexual abuse of children  so that it may prove useful for an ever greater good . He said all sectors of society, including  companies that promote and drive the development of the digital world,  have a responsibility to protect vulnerable children from forms of sexual abuse on the internet. The conference is also being addressed by Jacqueline Beauchere, the chief online safety officer for Microsoft and Antigone Davis, head of global safety policy for Facebook.  The three-day conference, which will present its findings to Pope Francis on Friday, will discuss themes such as bullying and the preying on children by pedophiles.  The kids aren t alright,  said Baroness Joanna Shields, founder of Britain s WeProtect, an alliance to end child exploitation online.  If a child s first lesson in sexual education is a pornographic video, then this will become their reference point,  she said. Professor Ernesto Caffo, the Italian founder of a 30-year-old hotline to report cases of endangered children, told the conference that 18 million children suffer sexual abuse in Europe and that there were more than 57,000 URLs containing child sexual abuse images. He said that in nearly 25 percent of cases, adult survivors of sexual abuse suffer from psychological problems, including depression, Post-Traumatic Stress Disorder (PTSD) and self harm. There was an urgent need to provide specialized training for professionals working in education, Caffo said. 