Investing.com - Crude prices rose to the best levels of the session on Wednesday, hitting a six-week high, after data showed that U.S. oil stockpiles fell unexpectedly last week as refinery activity picked up.

U.S. West Texas Intermediate (WTI) crude futures surged $1.04, or 1.6%, to $64.58 a barrel by 10:35AM ET (1435GMT). Prices were at around $64.25 prior to the release of the inventory data.

Meanwhile, London-traded Brent crude futures, the benchmark for oil prices outside the U.S., climbed $1.27, or roughly 1.9%, to $68.69 a barrel.

Both benchmarks hit their highest level since Feb. 5 earlier in the session.

The U.S. Energy Information Administration said in its weekly report that crude oil inventories declined by 2.6 million barrels in the week ended March 16.

That compared with analysts' expectations for a gain of around 2.6 million barrels, while the American Petroleum Institute late Tuesday reported a supply-drop of 2.7 million barrels.

Supplies at Cushing, Oklahoma, the key delivery point for Nymex crude, rose by 905,000 barrels last week, the EIA said.

Total U.S. crude oil inventories stood at 428.3 million barrels as of last week, which the EIA considered to be in the lower half of the average range for this time of year.

U.S. crude oil production rose by 0.3% from the previous week to a fresh all-time high of 10.40 million barrels per day, keeping it above Saudi Arabia's output levels and within reach of Russia, the world's biggest crude producer.

Analysts and traders have recently warned that booming U.S. shale oil production could potentially derail OPEC's effort to end a supply glut.

The report also showed that gasoline inventories decreased by 1.7 million barrels, compared to expectations for a decline of 2.0 million barrels. For distillate inventories including diesel, the EIA reported a drop of 2.0 million barrels.