On an annual basis, prices were down 1.9 percent after a 0.9 percent decrease in December, the statistics office said.
Prices for gas, electricity and heating rose 0.6 percent month-on-month in January, while mining industry prices dropped 0.8 percent and the processing industry dropped 1.9 percent.
The broader index of producer prices, including prices on the local market and for Bulgarian products sold internationally, dropped 1.2 percent in January from the previous month. It was down 2.9 percent year-on-year.