Oil prices up nearly 1 percent on soft dollar, OPEC speculation

Crude futures also rebounded from a selloff in the previous session on support from players buying on dips and looking for a bottom on speculation that next month's informal meeting between the Organization of the Petroleum Exporting Countries and other major producers could result in output curbs.

Some traders cited bullish data issued by energy monitoring firm Genscape showed a drawdown of more than 313,000 barrels at the Cushing, Oklahoma delivery point for US crude futures during the week to Aug. 23.

Brent crude futures LCOc1 rose 47 cents to $49.52 a barrel by 12:45 p.m. EDT (1645 GMT), after settling down 1.8 percent on Wednesday.

US crude's West Texas Intermediate (WTI) futures CLc1 rose 33 cents, or 0.7 percent, to $47.1. WTI lost nearly 3 percent in the previous session.

"There are two things going - wariness about the dollar tumbling after Friday's Fed event and bottom-fishing by players looking for more speculative support for the market ahead of a possible OPEC deal next month," a broker said.

The dollar DXY eased against a basket of currencies as some investors sold the currency before the annual global central bankers' gathering in Jackson Hole, Wyoming, where Yellen was to speak on US monetary policy on Friday. 

Recent US economic data has pointed to sluggish productivity and subdued inflation, suggesting the Fed could hold off on raising interest rates. The US central bank hiked rates for the first time in nearly a decade in December.