Oil rose for a third day on Thursday amid another drawdown in U.S. inventories and strong U.S. gasoline demand, while signs OPEC may not raise output to address shrinking supplies from Iran also supported prices.

Global benchmark Brent crude LCOc1 was up by 20 cents, or 0.3 percent, at $79.60 by 0214 GMT, after gaining half-a-percent on Wednesday, Reuters said.

U.S. West Texas Intermediate crude CLc1 was up 55 cents, or 0.8 percent, at $71.67 a barrel, after rising nearly 2 percent the previous session.

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U.S. crude oil stockpiles fell for a fifth straight week to 3-1/2 year lows in the week to Sept. 14, while gasoline inventories also showed a larger-than-expected draw on unseasonably strong demand, the Energy Information Administration said on Wednesday.

Crude inventories declined by 2.1 million barrels, the EIA data showed, compared with expectations for a decrease of 2.7 million barrels.

"The bulls are back in charge, even more so after traders were conveying a high degree of resistance to the unexpected build on the API survey," said Stephen Innes, head of trading for Asia-Pacific at OANDA in Singapore.

He was referring to the weekly survey from the oil industry group the American Petroleum Institute (API) on Tuesday that indicated U.S. stocks had risen by 1.2 million barrels last week.

U.S. sanctions affecting Iran's oil exports come into force on November 4 and many buyers have already scaled back Iranian purchases. But it is unclear how easily other producers can compensate for any lost supply.

The Organization of the Petroleum Exporting Countries and other producers including Russia meet on Sunday in Algeria to discuss how to allocate supply increases within their quota framework to offset the loss of Iranian supply.

OPEC sources have told Reuters no immediate action was planned and producers would discuss how to share a previously agreed output increase.