U.S. crude oil inventories fell for a sixth straight week, as OPEC efforts to reduce supply appear to be coming to fruition ahead of the cartel's upcoming meeting next week, while gasoline and distillate stocks also dropped.

The U.S. Energy Information Administration said on Wednesday that crude inventories fell 1.8 million barrels for the week to May 12, compared with expectations for a decrease of 2.4 million barrels.

That boosted oil prices immediately after the data, with U.S crude futures bouncing to a high of US$49.50 a barrel before retreating modestly. Crude was up 67 cents to US$49.32 a barrel as of 10:48 a.m. EDT (1448 GMT), though prices are still 8 percent below April's peak of US$53.76. Brent rose 81 cents to US$52.45 a barrel.

Traders and investors have grown increasingly concerned about a supply glut several months into the deal between the Organization of the Petroleum Exporting Countries and non-OPEC members like Russia to clip production by 1.8 million barrels per day.

Additional supply from other non-OPEC nations, like the United States, has offset the cuts. In the most recent week, U.S. production slipped 9,000 bpd to 9.305 million bpd, the first decline in 13 weeks. The EIA still expects U.S. production to average 9.31 million bpd in 2017.

Crude stocks have been edging lower after hitting a record 535.5 million barrels at the end of March. Total U.S. inventories now sit at 520.8 million barrels, a 3 per cent decline.

U.S. crude imports rose 577,000 bpd last week, while exports rose 400,000 bpd.

Some analysts viewed the drawdown in gasoline stocks disappointing, as they fell by just 413,000 barrels, compared with expectations in a Reuters poll for a 731,000-barrel drop.

"The numbers beneath the surface were rather mixed with gasoline stocks falling only slightly on weaker demand and sharply higher imports suggesting sufficient availability of crude oil internationally despite OPEC cuts," said Carsten Fritsch, oil analyst at Commerzbank AG in Frankfurt, Germany.

Refinery crude runs rose by 363,000 bpd as utilization rates rose by 1.9 percentage points to 93.4 per cent of total capacity. U.S. Gulf Coast refinery utilization rose 3.1 percentage points to 96.5 per cent, the highest level since August 2015, EIA data showed

Distillate stockpiles, which include diesel and heating oil, fell 1.9 million barrels, versus expectations for a 1.1 million-barrel drop, the EIA data showed.

Crude stocks at the Cushing, Oklahoma, delivery hub rose by 35,000 barrels, EIA said.