Oil prices had risen broadly earlier in the session after preliminary U.S. weekly jobless claims data hit a nearly 15-year low, indicating further strength in the world's largest economy.

But crude futures in New York were near a six-year low by midmorning after a report from oil services firm Genscape, which showed fresh builds of 1.6 million barrels at the Cushing, Oklahoma delivery point for U.S. crude in the period of Jan. 23 through Jan. 27, according to a market source.