Annual euro-zone inflation weakened further below the European Central Bank's target in December, rekindling fears that too little inflation or outright consumer-price declines may threaten the currency area's fragile economy.

The report puts pressure on ECB officials to maintain their ultra-loose monetary policy and consider additional stimulus measures to keep deflationary forces at bay.

However, it is unlikely to prompt a policy response from the ECB when it meets Thursday, analysts said, amid signs that the currency bloc remains on a path of gradual economic recovery led by its largest member, Germany.

Consumer prices were up 0.8% in December from the previous year, according to the European Union's statistics office, Eurostat, down from 0.9% in November. That is well below the ECB's target of a little below 2% over the medium term and just a touch higher than October's low of 0.7%, which spurred the ECB to cut its main interest rate to a record-low 0.25% two months ago.

After stripping out prices for food and energy, which tend to be more volatile, prices rose by just 0.7% in the 12 months to December—the lowest rate of "core" inflation since records began in January 2001.