Oil prices have risen slightly amid concern that Israeli attacks on Hamas could disrupt crude oil supplies from the Middle East.
US light, sweet crude was up 18 cents at $37.89 per barrel by 1.28pm EST (1828 GMT) on Monday.
London Brent crude rose 33 cents to $US38.70 per barrel.
Oil is on track for a loss of almost 60% this year after reaching a record price of $US147.27 per barrel on 11 July. A downturn in the world economy has hit demand for fuel since then.
Israeli aircraft have attacked Hamas targets in Gaza for three days, killing more than 300 Palestinians. The attacks have enraged Arabs across the Middle East.
Members of the Organization of the Petroleum Exporting Countries agreed on 17 December to cut supplies by 2.2 million barrels per day. OPEC has now cut output three times this year to counter the slide in prices.