U.S. oil stocks up on imports, refining slowdown: API

A safety flare is seen at the Valero St. Charles oil refinery during a tour of the refinery in Norco, Louisiana August 15, 2008.

NEW YORK (Reuters) - U.S. crude oil stockpiles surged unexpectedly last week as imports sped up and refiners slowed their processing rates, the American Petroleum Institute said on Tuesday.

Commercial inventories of crude oil rose by 4.1 million barrels to 352.4 million barrels, bringing them 49.8 million barrels above last year's levels, the API said in its weekly report.

Oil analysts had expected inventories to decline by 1.3 million barrels, according to a Reuters survey.

The surprise build came as imports increased by an average of 199,000 barrels per day to 9.12 million bpd, and refiners slowed crude throughputs by 75,000 bpd, according to the report.

Refined products inventories, meanwhile, were close to unchanged, with gasoline stocks down 47,000 barrels and distillate stocks up 116,000 barrels.

Analysts had expected the report to show gasoline stocks up 400,000 barrels and distillate stocks up 1.3 million barrels, according to the Reuters survey.

U.S. crude oil prices traded down $1.67 to $66.71 a barrel after the report.

"The API build of 4.1 million barrels is bearish and NYMEX crude fell back after release of the data," said Gene McGillian, analyst at TFS Energy in Stamford, Connecticut. "But we still have to see whether the DOE will confirm this number tomorrow."

The U.S. Energy Information Administration, the statistical wing of the Department of Energy, will release its petroleum inventory report Wednesday morning.

(Reporting by Richard Valdmanis and Gene Ramos; Editing by David Gregorio)