Oil prices ended mildly higher Friday as investors digested U.S. Federal Reserve's Chair Janet Yellen's comments on rate hikes.

"In light of the continued solid performance of the labor market and our outlook for economic activity and inflation, I believe the case for an increase in the federal funds rate has strengthened in recent months," Yellen said Friday in a speech to a conference of central bankers in Jackson Hole, the U.S. state of Wyoming.

Pointing to solid growth in household spending and a strengthening job market, Yellen said that the U.S. economy is "now nearing" the Fed's statutory goals of maximum employment and price stability.

Analysts said it's possible for the Fed to hike interest rates as soon as September. But about 71 percent of 62 economists surveyed by the Wall Street Journal this month believed that the Fed will wait until December to raise rates.

Meanwhile, oilfield services company Baker Hughes said Friday that the number of rigs operating in U.S. fields was unchanged at 406 this week.

On the economic front, the U.S. economy grew at an annual rate of 1.1 percent in the second quarter this year, down from a previous estimate of 1.2 percent, the Commerce Department said Friday.

The West Texas Intermediate for October delivery increased 0.31 U.S. dollar to settle at 47.64 dollars a barrel on the New York Mercantile Exchange, while Brent crude for October delivery added 0.25 dollar to close at 49.92 dollars a barrel on the London ICE Futures Exchange.

Source : XINHUA