MANILA, Dec 15 (Reuters) - The Philippine central bank raised its benchmark interest rates by half a percentage point on Thursday, opting for a relatively large increase to cool inflation running at a 14-year high.

The rate hike was a certainty after Bangko Sentral ng Pilipinas (BSP) Governor Felipe Medalla flagged a 25 to 50 basis point adjustment this month ahead of November inflation data.

Annual inflation surged to 8.0% in November, which was well above the BSP's target range of 2% to 4% for this year, reinforcing the case for a half-percentage point increase and suggesting more tightening could follow next year.

All 21 economists in a Reuters poll correctly predicted the outcome of Thursday's BSP policy meeting, which was the last for the year. The decision marked the seventh time this year that the central bank has pulled the rate-hike trigger to combat inflation.

Thursday's 50-bps rise matched the U.S. central bank's latest move. The BSP therefore kept steady its interest rate gap with Federal Reserve, supporting the Philippine peso, whose recent weakness has pushed up already elevated consumer prices.

After the Philippine tightening, which took the overnight borrowing rate to 5.50%, analysts expect the BSP to end its tightening cycle at 6.00%, compared with the expectation of 5.75% in a Reuters poll in November.

(Reporting by Neil Jerome Morales and Karen Lema; Editing by Himani Sarkar and Bradley Perrett)