(Reuters) – U.S. crude oil stockpiles rose unexpectedly last week and gasoline inventories surged by their most in a week in four years, the Energy Information Administration said on Wednesday.

  Crude inventories rose by 1.2 million barrels in the week ended Jan. 3 to 431.1 million barrels, compared with analysts’ expectations in a Reuters poll for a 3.6 million-barrel drop.

    U.S. gasoline stocks surprised as well, rising by 9.1 million barrels in the week to 251.6 million barrels, compared with expectations in a Reuters poll for a 2.7 million-barrel rise. That was the largest one-week gain in gasoline inventories since January 2016.

Analysts blamed recent weak demand figures, as gasoline supplied over the last four weeks ​was 0.4% lower than the same period a year ago.

“Both distillates and gasoline managed to muster large builds as demand remains both subdued and below year-ago levels on the four-week average,” said Matt Smith, director of commodity research at ClipperData.

Oil prices slipped on the data, as the market was already backtracking from recent gains spurred by escalating tensions between the United States and Iran.

U.S. crude futures were down 1.9%, or $1.19, to $61.51 a barrel by 10:55 a.m. ET (1555 GMT). Brent futures were off by 1.4%, or 95 cents, to $67.31 a barrel.

“The market is already nervous, sucking risk premium out, and then you get a surprise bearish report and it doesn’t help,” said Phil Flynn, an analyst at Price Futures Group in Chicago.

    Refinery crude runs fell by 386,000 barrels per day last week, the EIA said. Refinery utilization rates fell by 1.5 percentage points to 93% of total capacity.

    Distillate stockpiles, which include diesel and heating oil, rose by 5.3 million barrels in the week to 139 million barrels, versus expectations for a 3.9 million-barrel rise, the data showed.

    Net U.S. crude imports rose by 1.78 million bpd, the EIA said.

    Crude stocks at the Cushing, Oklahoma, delivery hub fell by 821,000 barrels in the last week, EIA said.