US crude oil futures fell 90 cents to $82.03 a barrel by 1823 GMT. ICE Brent crude lost 54 cents to $81.42.

Prices rose more than $3 in the previous two days due to larger-than-expected decreases in fuel inventories in the United States and strong US gasoline demand, which rose to a record high for the month of February.

Ministers from the Organization of the Petroleum Exporting Countries (OPEC) agreed on Wednesday to maintain the official existing cuts of 4.2 million barrels per day.

World stocks dropped on Thursday and the euro weakened against the US dollar on renewed worries about Greece, which said it may be unable to solve its fiscal problems if borrowing costs stay high.

Adding to the moves in currencies, traders linked the euro's selling to rumors the US Federal Reserve would hike the discount rate. Asked about the speculation, the Fed said it does not comment on rumors.

The euro fell to session lows against the US dollar of $1.3587 before recovering to $1.3619 at midday in New York, according to Reuters data. The MSCI's all-country world stock index dipped 0.46 percent while its emerging market-only counterpart fell 0.47 percent.

Greece raised the stakes in its quest for EU help to tackle its debt crisis, saying it cannot achieve promised deficit cuts if its borrowing costs remain so high and may have to call in the IMF.

"This just highlights the uncertainty surrounding the Greece issue. There seems to be no consensus in the euro zone, which is undermining confidence and that is what is weighing on the euro today," said Antje Praefcke, currency strategist at Commerzbank.

The pan-European FTSEurofirst 300 index of shares dropped 0.11 percent to end at 1,068.93 points, while the Nikkei 225 Index fell 0.95 percent.

The Dow Jones Industrial Average was up 27.59 points, or 0.26 percent, at 10,761.26, during mid-day trading. But the benchmark Standard & Poor's 500 Index was down 2.35 points, or 0.20 percent, at 1,163.86, while the Nasdaq Composite Index was up 0.21 point, or 0.01 percent, at 2,389.30.

US Treasury debt prices fell on looming supply, overshadowing tame inflation data. The benchmark 10-year US Treasury note was down 8/32, with the yield at 3.6702 percent, while the 2-year US Treasury note was down 3/32, with the yield at 0.9601 percent.

At the longer end of the Treasury curve, the 30-year US Treasury bond was down 11/32, with the yield at 4.591 percent.

The dollar was up against a basket of major trading-partner currencies, with the US Dollar Index up 0.72 percent at 80.214 from a previous session close of 79.638. Against the Japanese yen, the dollar was down 0.03 percent at 90.24 from a previous session close of 90.270.