Oil prices added to their losses on Thursday after the Energy Information Administration (EIA) showed a surprise buildup of 1.1 million barrels in U.S. crude inventories, indicating weak demand from the world's biggest energy consumer.

U.S. crude futures fell half a dollar, or 1.22% to trade at $41.20 a barrel, after hitting a one-week trough at $41.11, while Brent crude futures shed 47 cents, or 1.07% to hover around $43.59 a barrel.

The dollar index on the other hand recovered some of its heavy losses on short-covering, rising 0.25% to 95.83, while the greenback battered sterling by 0.43% to 1.2957. The euro slid 0.32% to 1.1143.

Gold prices were largely flat for the day, with the futures down half a dollar, or 0.04% to trade at $1,351 an ounce, while silver futures gained a cent, or 0.07% to hover around $20.18 an ounce.

Investors await a bunch of U.S. data later today, with unemployment claims expected to rise to 272 thousand last week from the previous reading's 269K, which would be slightly negative for the economy.

U.S. import prices are expected to have fallen 0.2% m/m in July, compared to a 0.2% rise in June, which again is a negative for the economy and the dollar as it indicates weak inflation.