Krenn has called the photos a "schoolboy prank"

Several pressure groups have called on Bishop Kurt Krenn to quit, after child pornography was allegedly found at a Catholic priests' training college.

Bishop Alois Schwarz urged the Vatican to intervene, saying only the Church itself could resolve the crisis.

As many as 40,000 sexual images were allegedly found, but Bishop Krenn has dismissed them as a "schoolboy prank".

Officers confiscated computer hard drives from the seminary at St Poelten, about 80km (50 miles) west of the Austrian capital, Vienna.

Internal inquiry

The news magazine Profil said photographs showed senior clerics kissing and fondling trainees.

Pictures of children were also allegedly found.

Bishop Krenn, 68, has brushed off the calls for his resignation.

On Wednesday, he launched an internal inquiry into the affair.

But the pressure on him from Catholic groups and fellow bishops is building.

"Like many people in Austria, I am also stunned by the events portrayed in the priestly seminary in St Poelten and their repercussions on the Church in all of Austria," Bishop Schwarz said.

'Wrong picture'

"I am hoping for swift decisions that leave no questions open."

Liberal group We Are the Church said Bishop Krenn must step down as "the diocese today is practically leaderless and split".

Austria's largest organisation for Catholic churchgoers, OCV, urged the Church to use some "crisis management" to defuse the scandal, which "gives a completely wrong picture of the Catholic Church in Austria".

The director of the seminary, Ulrich Kuechl, has already resigned, as has his deputy Wolfgang Rothe.