Envelopes containing 10,000 yen (US$82; euro60) bills and well-wishing notes have been discovered in municipal toilets across Japan, media reports said, baffling civil servants and triggering a nationwide hunt.

Local media have estimated that over 2 million yen (US$16,400; euro12,000) worth of bills were found at men's rooms in city halls in at least 15 prefectures (states) in recent weeks.

Each package of 10,000-yen bills, some wrapped in traditional Japanese washi paper, was accompanied by handwritten letters that read "Please make use of this money for your self-enrichment," and "One per person," according to reports.

Officials are baffled over the identity of the benefactor or any motives, the reports said. Packages turned over to police were to be kept for some time in case someone claimed them.