WINDSOR, Ont. - A Canada-wide arrest warrant has been issued for a Vatican diplomat accused of uploading child pornography to a social networking site while inside a Windsor, Ont., church over the Christmas period last year.

Windsor police say they were alerted by the RCMP in February and launched an investigation, eventually getting judicial permission to access relevant internet records.

They say the alleged offences took place between Dec. 24 and 27 of last year.

Police say the 50-year-old suspect has since returned to his home in Italy, and also has ties to the United States as well as the Windsor area.

Carlo Capella is sought on charges of accessing, possessing and distributing child pornography.

The Vatican recalled Capella after the U.S. State Department notified it Aug. 21 of a "possible violation of laws relating to child pornography images" by one of its diplomats in Washington.

The Vatican - while not mentioning Capella by name - says its own prosecutor is investigating and seeking further information from the U.S.

The Diocese of London, Ont., confirmed that it helped investigators who had suspicions of "possible violations of child pornography laws by using a computer address at a local church."

It declined further comment, citing a police request.

The diplomat's recall was expected to loom over an international conference next week at the Pontifical Gregorian University in Rome on protecting children from online sexual exploitation, pornography and abuse.

Cardinal Pietro Parolin, the Vatican secretary of state and Capella's boss, is set to deliver the keynote speech Tuesday on "The Holy See and its commitment to combating sex abuse online."

Panelists at the conference, which was organized months ago, are to include top law enforcement and academic experts in the field of child protection and cybercrimes, with an entire morning devoted to "Child Sexual Abuse Online: Who are the offenders?"