The Rev. John Olav Hodne, a parish priest at a church near Trondheim, discovered the theft when he went into to the sacristy after service Sunday, TheLocal.no reported Monday.
"I assume that the thief must have come into the sacristy without going through the church," police official Ebbe Kimo told Norway's public broadcaster NRK. "It is a particularly disagreeable and unusual theft."
Kimo said police had decided to alert the public to the robbery, hoping someone may have seen something unusual at the church.
"We hope that the matter gets a little attention so we can get some tips," he said. "It could be that someone saw something suspicious around Melhus church this morning."
When contacted by TheLocal.no, Hodne expressed suspicion about the call and asked whether the caller was the thief.
"Do you have my phone and my credit cards and everything?" the priest said. "I don't understand how this got into the [national] news and I won't answer any questions until I understand what has happened."