The explorers are focusing on three sites inside the fenced-off area. Tomasz Siwiec, the coordinator of the project, said in an interview on Wednesday that excavations of two of the sites had to be halted on Tuesday afternoon when the team encountered rocks that could be removed only by a jackhammer.

But during the third dig, Mr. Siwiec said, the team came across some materials that struck them as odd. “We have found pieces of decades-old porcelain, which may come from a porcelain factory that used to be here before the war, as well as some lake clay,” Mr. Siwiec said. “There are no lakes in the vicinity.” He speculated that the debris and clay had been used, along with dirt, “to bury the tunnel we are looking for.”

“We just intend to locate whatever there is to locate,” he said, “but getting it out rests with the Polish authorities.”

At the end of the second day of digging, Mr. Gaik and Adam Szynkiewicz, a geologist involved in the project, said that even though the excavators had gotten down to nine meters, they still had not found anything, showing that their initial estimates that the tunnel would be eight meters below ground, and the train nine meters below ground, had been too optimistic. “We will just have to go two to three meters deeper,” Mr. Gaik said. “If we still have nothing at that depth, we will try another place.”

Residents reacted with a mixture of curiosity and amusement. Anna Kreta, 60, a retired postal worker from a nearby town, Swiebodzice, said she had heard legends of buried treasure since she was little. “It’s not news to me, but it’s still the No. 1 topic for everyone,” she said.

Walbrzych has been struggling with high unemployment since three coal mines here closed in the 1990s.