US crude stockpiles jumped by more than expected in the week, government data showed, adding to pressures on futures of the commodity which spiraled lower in Wednesday’s session.

West Texas Intermediate, the main US variety, was down 3.7% to $64.57 a barrel at the time of writing, erasing all of the gains it made in July. Brent, the international standard, was about 3% weaker to $70.36 a barrel the lowest in about four months on a closing basis.

US commercial crude oil inventories rose by 6.8 million barrels in the week ending Aug. 10 to 414.2 million barrels, data from the Energy Information Administration showed.

That’s compared with the prior week’s decrease of 1.4 million barrels and the American Petroleum Institute’s forecast for an increase of about 3.7 million barrels. The EIA said the new figures show crude inventories are about 1% above the five-year average for the time of year.

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Total motor gasoline inventories decreased by 0.7 million barrels in the week, less than the API’s forecast for a drop of about 1.56 million barrels and compared with the previous period’s rise of 2.9 million barrels.

Oil had surged higher in recent weeks as the US began imposing sanctions on Iran, but broader worries about global growth amid brewing trade disputes and a financial crisis in Turkey has added to pressure on markets across the world, and crude prices have skidded lower this week.

In the US, refinery operations rose to 98.1% of capacity from 96.6%, with inputs averaging about 18 million barrels per day during week, up 383,000 barrels more than the prior week, the EIA said.

Distillate fuel inventories rose by 3.6 million barrels from a gain of 1.2 million barrels in the prior period. And propane/propylene inventories were up by 3.4 million barrels in the week, compared with an increase of 0.1 million barrels in the week earlier.

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