Behind the strength of international oil prices are such factors as decreased investment in new oil fields, brisk demand from Asia and other regions, expectations for the extension of a production cut by the Organization of Petroleum Exporting Countries and growing instability in the Middle East, market analysts said.

"Crude prices were bullish in November in anticipation of an OPEC decision to extend the output reduction," said Kim Hun-gil, an analyst at Hana Financial Investment Co. "The price hike was also fueled by speculative purchases of oil futures."

Late last month, OPEC decided to extend their production cut for an additional nine months, and some watchers predicted oil prices to move in a narrow band due to an increase in US shale oil output.

"Oil prices are unlikely to rise far above the mid-$50-per-barrel level for the time being as US shale companies move to jack up their production," Kim said.

Oh Eun-soo, an analyst at KB Securities Co., projected international oil prices to rise further next year due to heightened geopolitical instability following the recent US recognition of Jerusalem as Israel's capital. (Yonhap)