VATICAN CITY (Reuters) - Pope John Paul II, reacting unusually swiftly to a sex and child pornography scandal that has shaken the Austrian Roman Catholic Church, named a special investigator Tuesday to probe the affair.

A brief statement said the pope had named Bishop Klaus Kung of the Austrian city of Feldkirch to look into the problems of the diocese of St Poelten and in particular a seminary at the center of the allegations.

The fresh scandal in predominantly Catholic Austria is another blow for the Roman Catholic Church after a series of shocking sexual abuse cases involving clergy across the world.

Vienna Archbishop Cardinal Christoph Schoenborn said the pope had acted quickly and called it an "extraordinary measure."

News that police had seized seminary computers to check for child pornography came out in May but the scandal erupted when news magazine Profil ran pictures last week of priests kissing and groping students studying for the priesthood.

The rapid Vatican response contrasted with its slow reaction to a big sex abuse scandal in the U.S. Church in 2002 when months passed before action was taken.

Austrian prosecutors charged a seminarian Monday with downloading child pornography from the Internet and said he was not the only person at the seminary to have done so.

Prosecutors in St Poelten, west of Vienna, said they found child pornography on the seminary's main computer and on one owned by a 27-year-old seminarian from Poland, who could be jailed for up to two years if convicted.

INQUISITORS

The Vatican calls its investigators "apostolic visitors." But despite the genteel title, they are more like inquisitors, who report back to the pope with recommendations for action.

Kung said he would start his investigation immediately and would "move ahead thoroughly and swiftly."

St. Poelten Bishop Kurt Krenn, who is responsible for the seminary, has refused calls to resign over the scandal.

The director of the seminary and his assistant, who appeared in the pictures published by Profil, have stepped down.

The Vienna archdiocese said in a statement the investigator would also look into the conduct of Krenn's office and all diocese establishments.

Krenn said he expected a "thorough, scrupulous and objective inspection" of his diocese and seminary.

In 1995, Profil published charges that Cardinal Hans Hermann Groer, then head of Austria's Catholic Church, had sexually abused boys. The Vatican replaced him months later. He retired to a monastery and died last year.

The Vatican is still reeling from the U.S. scandal of 2002, when it was discovered that bishops had moved priests known to have sexually abused minors from one assignment to another instead of defrocking them or reporting them to the police.

Two U.S. reports showed more than 10,600 children said they had been molested by priests in the United States since 1950.

The U.S. Church has paid nearly $700 million in damages to abuse victims, including some $85 million paid out by the Archdiocese of Boston, the epicenter of the crisis.