Brent crude moved above $71 a barrel for the first time in three years on Thursday, pushed higher by the weakening dollar despite inventory data that showed US stockpiles increased last week.
The global crude oil benchmark climbed as high as $71.06 a barrel in early trade and by the time European markets were opening it stood 0.55% higher at $70.92.
Nymex West Texas Intermediate, the US benchmark crude price, rose 0.9% to $66.20.
Dollar-denominated commodities were mostly higher on the commodity futures exchanges as the US currency continued to slide.
The dollar index, a measure of the greenback's relative strength against a basket of its six main rivals, fell a further 0.12% to 89.09 on Thursday. The measure is down 3.3% since the start of the year.
A weaker US currency presents an attractive buy signal for commodity investors as it makes purchases of dollar-denominated assets less expensive in rival currencies.
US backs weaker dollar
The dollar's recent losses appeared to win backing from the US Treasury this week after Steven Mnuchin, Treasury Secretary (left), speaking on Wednesday at the Davos World Economic Forum, said: "A weaker dollar is good for us as it relates to trade and opportunities."
Historically, the Treasury's official line has been to back a strong dollar - regardless of whether dollar strength is an economic benefit - to encourage investment in US assets, particularly US Treasury securities.
Oil prices rose in spite of data that showed US crude oil inventories increased by 4.8 million barrels last week, according to the American Petroleum Institute (API).
The API data also showed that gasoline stocks increased by 4.1 million barrels.