BANGKOK, Nov 5 (Reuters) - Thailand's headline consumer price index (CPI) in October jumped more than expected and at the fastest pace in five months, driven by higher oil and vegetable prices, the commerce ministry said on Friday.

The CPI climbed 2.38% in October from a year earlier, compared with a forecast for a rise of 1.91% in a Reuters poll and against September's 1.68% increase.

The CPI is likely to increase later this year, though not sharply, due in part to government measures to support oil prices, senior ministry official Ronnarong Phoolpipat told a news conference.

It is projected to rise by 2.43% in the fourth quarter year-on-year, he said.

For 2021, the ministry is maintaining its forecast for headline inflation of 0.8% to 1.2%, he added.

In October, the core CPI index was up 0.21% from a year earlier, compared with a forecast for a 0.30% rise.

In the January-October period, the headline CPI rose 0.99% from a year earlier, with the core rate up 0.23%.

(Reporting by Orathai Sriring, Kitiphong Thaichareon and Satawasin Staporncharnchai; Editing by Martin Petty)