Oil eased on Wednesday after closely watched data showed a surprise rise in United States (US) crude stockpiles, but prices were supported by mounting tensions in West Asia.

Brent crude futures were at $70.90 a barrel at 0100 GMT, down 41 cents, or 0.7 per cent, from their last close. Brent closed up 1.4 per cent on Tuesday.

US West Texas Intermediate (WTI) crude futures were at $61.39 per barrel, down 24 cents, or 0.3 per cent, from their previous settlement. WTI closed up 1.2 per cent in the previous session.

US crude stockpiles unexpectedly rose last week, while gasoline and distillate inventories increased, data from industry group the American Petroleum Institute showed on Tuesday.

Oil prices have drawn support after Saudi Arabia said that armed drones struck two of its oil pumping stations, two days after the sabotage of oil tankers near the United Arab Emirates (UAE).

The US military said it was braced for ”possibly imminent threats to US forces in Iraq” from Iran-backed forces.

The attacks took place against a backdrop of US-Iranian tension following Washington's decision this month to try to cut Iran's oil exports to zero and to beef up its military presence in the Gulf in response to what it said were Iranian threats.

Meanwhile, the Organisation of the Petroleum Exporting Countries (OPEC) on Tuesday said that world demand for its oil would be higher than expected this year as supply growth from rivals including US shale producers slows, pointing to a tighter market if the exporter group refrains from raising output.