Oil prices recouped some of their heavy losses this week on short-covering after touching nearly four-month lows yesterday on worries of a global supply glut in a time when demand slips, specially in the U.S., the world's largest energy consumer.

U.S. crude futures rose 26 cents, or 0.63% to trade at $39.76 a barrel, still below the psychological level of $40, and not far from a four-month trough hit yesterday at $39.26, while Brent futures added 32 cents, or 0.77% to $42.11 a barrel.

The dollar edged higher today after a similar streak of tumbles, with the index up 0.18% to 95.19, while the greenback advanced 0.21% against the euro to trade at 1.1200.

Japan's Nikkei index widened its losses sharply, tumbling another 1.88% to 16,083 and setting a fresh three-week low, while the pan-European FTSEurofirst 300 index opened modestly lower to 1,320, with a 0.06% loss.

Investors await a stream of data later, with the U.S. final services PMI for July expected to fall to 50.9 from June's 51.0, which would add to worries over the strength of the American economy after earlier data showed dismal GDP growth in the second quarter.

U.S. crude oil inventories are forecast to have fallen 1.6 million barrels last week, compared to a 1.7M addition in the week before, which would prop up prices further from their recent lows.