Japan's core consumer prices fell for the eighth month in a row in March and analysts expect further drops ahead due to the drag from mobile phone fee cuts.

This will keep Japan's central bank under pressure to maintain its massive stimulus to fire up inflation.

A spike in new Covid-19 infections and the government's plan to declare a third state of emergency from Sunday may also weigh on inflation by hitting already weak consumption, boding ill for a fragile economic recovery.

The core consumer price index (CPI), which includes oil products but excludes volatile fresh food prices, slid 0.1% in March from a year earlier, government data showed today, matching a median market forecast.

The pace of decline slowed from 0.4% in February due mostly to a rebound in petrol costs, as hopes of a strong global economic recovery pushed up crude oil prices in recent months.

While the base effect of last year's plunge in energy costs may underpin consumer prices, that may be more than offset by mobile phone fee cuts by major carriers that will be incorporated into the data from April, analysts say.

Mobile phone charges will be particularly cheaper for plans that only accept applications online, which is also expected to be incorporated into CPI data from April, a government official told a briefing.

While the government does not disclose how much the phone fee cuts could affect CPI, analysts expect them to push down the core index by up to 0.6% points.

The Bank of Japan is expected to cut its inflation forecasts when it issues fresh quarterly projections at next week's rate review, partly reflecting the expected fee cuts.

While the drop in fees would give households more purchasing power, the weakness in underlying inflation may hamper the Bank of Japan's efforts to shift public perceptions that prices will keep falling, and coax consumers into spending now rather than save.

Japan's economy has been slowly recovering from last year's severe slump triggered by the Covid-19 pandemic.

But activity is expected to have contracted against in the three months from January to March and may rebound only modestly in the current quarter as fresh emergency curbs hurt consumption.