Oil prices keep rising

Oil rose for a third day by more than $4 to more than $120 a barrel on Thursday, as Poland's missile deal with the US angered Russia and fueled international tensions.

According to analysts, the missile shield agreement is one of a number of geopolitical factors that have influenced oil prices over the recent months.

"There's a myriad of geopolitical factors rumbling in the background - Russia, Iran," said Tony Machacek, a broker at Bache Commodities Ltd. to Reuters. "Also, the dollar is weaker." The U.S. crude gained $4.22 to $119.78 a barrel on Thursday.

Poland and the US signed a missile defense deal on Wednesday to station interceptor missiles on its soil, a move that has drawn sharp criticism from Russia. Russia, which is one of the world's largest oil producers, has criticized Washington with its missile plans from the beginning. Russian's invasion of Georgia has also sent oil prices to climb as the conflict has cut some export routes.

Sources: Reuters, Bloomberg