U.S. crude oil stockpiles rose unexpectedly last week even as refineries hiked output to the highest in five months, while gasoline stocks increased sharply as demand eased, the Energy Information Administration (EIA) said June 6.

Crude inventories rose by 2.1 million barrels (bbl) in the week to June 1, compared with analysts' expectations for a decrease of 1.8 million bbl.

The bulk of that build was due to a sharp increase in stocks on the West Coast, where inventories jumped 2.5 million bbl, the EIA said.

Oil prices fell on the data. U.S. crude futures dropped $1.19 to $64.34/bbl, while Brent crude fell 81 cents to $74.56/bbl as of 9:51 a.m. CDT (14:51 GMT). The spread between U.S. crude and Bren widened by about 4% to more than $10/bbl.

Refining crude runs and rates hit their highest levels since late December as facilities came back online after periods of maintenance. Refinery crude runs rose 214,000 barrels per day (bbl/d) to 17.4 million bbl/d and utilization rates rose by 1.5 percentage points to 95.4% of available capacity, EIA data showed.

Gasoline stocks rose by 4.6 million bbl, compared with analysts' expectations for a 587,000-bbl gain.

Distillate stockpiles, which include diesel and heating oil, rose by 2.2 million bbl, vs. expectations for a 784,000-bbl increase, the EIA data showed.

Net U.S. crude imports rose last week by 1.2 million bbl/d.

Crude stocks at the Cushing, Okla., delivery hub fell by 955,000 bbl, the EIA said.