HONG KONG (Bloomberg) -- Oil extended its decline after the biggest loss in six weeks, as rising U.S. crude stockpiles kept supplies at the highest level in more than eight decades.

Futures dropped as much as 1.6% in New York after slumping 4% Wednesday, the most since Feb. 11. Inventories rose by more than three times what was projected in a Bloomberg survey, while imports last week increased to the highest since June 2013, Energy Information Administration data showed. Iraq will attend a meeting between major exporters in Doha next month, according to an oil ministry spokesman.

“It’s a globally oversupplied market,” Ric Spooner, a chief analyst at CMC Markets in Sydney, said by phone. “U.S. imports were very strong, and as a consequence, there was a very big build in crude inventories. On the positive side, we do seem to have a gradual, trending decline in production.”

Oil tumbled to a 12-year low this year before rebounding on speculation the global surplus will ease as U.S. production declined. Crude stockpiles at Cushing, Okla., the delivery point for West Texas Intermediate and the nation’s biggest oil-storage hub, dropped for the first time in eight weeks, falling from a record, EIA data showed Wednesday.

WTI for May delivery slid as much as 62 cents to $39.17/bbl on the New York Mercantile Exchange and was at $39.27 at 8:04 a.m. London time. The contract fell $1.66 to $39.79 Wednesday. Total volume traded was about 25% below the 100-day average. Front-month prices are down 0.4% this week, heading for the first weekly drop in six weeks.

U.S. Inventories

Brent for May settlement lost as much as 42 cents, or 1%, to $40.05/bbl on the London-based ICE Futures Europe exchange. The contract declined $1.32 to $40.47 on Wednesday. Prices are down 2.5% this week. The global benchmark crude was at an 91-cent premium to WTI.

U.S. crude stockpiles increased by 9.36 MMbbl to 532.5 MMbbl, the highest level since 1930, according to data from the EIA. Imports rose for the first time in three weeks to 8.38 MMbopd. Production fell to 9.04 MMbopd, the lowest level since November 2014.