Jan Drob, financial officer of Poland's Roman Catholic Bishops' Conference, said church leaders were particularly looking for police advice on protecting 15th- and 16th-century wooden churches, because most of them contained valuable statues, sculptures and crosses and were especially vulnerable to arson and theft.

"The thieves know church protection is lax since many parishes with valuable objects can't afford security devices," Drob said. "People will steal whatever they can—this is the main problem."

Last month the bishop of Lowicz, Alojzy Orszulik, threatened to excommunicate thieves who had made off with the crown from a madonna in his cathedral unless they returned it and did penance.

The crown has not been returned, and the bishop has hired a private detective and offered a 10,000 zloty (U.S. $2,500) reward for its return—a recompense 10 times more than the crown's value, according to a Polish television report.

The new security campaign reflects growing concern about security at the 9000 Roman Catholic parishes in Poland, where armed robberies have quadrupled since the early 1990s, according to police.

"Priests' houses have to be open places," said Inspector Pawel Biedziak, spokesman for Poland's central police headquarters. "But we're concerned they should be better protected."

"The criminals know a lonely old priest in his residence won't put up a struggle," the inspector continued. "Those involved are invariably third-rate crooks with a weak command of mathematics. They don't realize that, however much is placed in collection plates, priests keep little money at home."

Last summer, a ...