MANILA, Jan 5 (Reuters) - The Philippines' annual inflation was at 3.9% in December, down slightly from the previous month's 4.1%, the statistics agency said on Friday.

Economists in a Reuters poll had forecast annual inflation of 4.0% in December, within the central bank's 3.6% to 4.4% projection for the month. (Reporting by Neil Jerome Morales and Mikhail Flores)