"We had never heard of anything like this a few years ago, but there have been several cases near here in recent months," said a spokesman for the Uehara Buddhism Museum, in the port town of Shimoda.

"Maybe it is because fewer people are going to temples now that it is easier to steal things," he said, adding that the religious icons are apparently passed on directly to specialist collectors or sold at auctions in large cities, where there is less chance of their origins being questioned.

Two dealers in antiquities have been arrested in recent months on suspicion of stealing a statue of a deity dating from the Muromachi Period, more than 430 years ago, and replacing it with a copy.

Valued at some Y3 million (£18,000), the original statue was sold at an auction in June but recovered earlier this month. The dealers are believed to have been behind the theft of dozens of statues in the last 18 months.

Similar thefts have been reported from religious facilities that are seen as similarly soft targets in other rural prefectures across Japan.