By Georgi Kantchev 

LONDON--Oil futures rose on Thursday as the dollar weakened and Russia continued its military operations in Syria, though the global glut of crude continued to weigh on prices.

Russia escalated its assault on opponents of Bashar al-Assad's regime with its first naval bombardment on Wednesday, a week after Moscow began its campaign in the war-torn country. The intervention added to the uncertainty in the Middle East, one of world's biggest oil producing regions.

"The Syrian army's Russian-supported ground offensive is likely to have lent support to prices," analysts at Commerzbank said.

Brent crude, the global oil benchmark, rose 0.3% to $51.94 a barrel on London's ICE Futures exchange. On the New York Mercantile Exchange, West Texas Intermediate futures were trading up 0.3% at $47.93 a barrel.

On Thursday, The Wall Street Journal Dollar Index, which tracks the dollar against a basket of other currencies, fell 0.2% ahead of the release of the minutes from the last Federal Reserve meeting. As oil is priced in dollars, it becomes more expensive for holders of other currencies as the greenback appreciates.

Doubts about the lifting of the sanctions against Iran also boosted prices. Iran and six major world powers led by the U.S. reached a landmark deal in July to limit Tehran's nuclear program in exchange for lifting of international economic sanctions. That is crucial for the oil market as it would pave the way for a substantial increase in Iranian oil production adding to the global oversupply.

But the Islamic Republic's Supreme Leader Ayatollah Ali Khamenei on Wednesday barred direct talks with the U.S. beyond the current nuclear negotiations, saying the U.S. would use them to undermine Tehran.

"This might lead some to question whether striking a final deal and lifting sanctions will go smoothly in the face of opposition from hardliners in both countries," analysts at JBC Energy said in a report.

Meanwhile, the U.S. Energy Information Administration reported on Wednesday that total commercial supplies of crude oil and petroleum products in the country rose by 2.3 million barrels last week to 1.3 billion barrels, a record high in data going back to 1990. U.S. oil production also rose, bucking its recent downward trend and adding to doubts that a sharp fall in U.S. output is imminent.

"If such doubts were to gain the upper hand, oil prices would presumably shed their latest gains again. After all, the expectation of a pronounced decrease in production was one major reason for the price rise in recent days," Commerzbank said.

Nymex reformulated gasoline blendstock--the benchmark gasoline contract--fell 0.1% to $1.39 a gallon. ICE gasoil changed hands at $481 a metric ton, down $7.75 from the previous settlement.

Write to Georgi Kantchev at georgi.kantchev@wsj.com

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(END) Dow Jones Newswires

October 08, 2015 05:50 ET (09:50 GMT)