Oil prices tumbled on Thursday after another big weekly build in U.S. crude inventories and a possible rise in Saudi output stoked worries about oversupply. U.S. crude stocks rose by 14.3 million barrels last week, data from industry group the American Petroleum Institute (API) showed after Wednesday’s settlement, compared with analysts’ expectations for an increase of 3.2 million barrels. If U.S. Energy Information Administration (EIA) data due at 1600 GMT confirms the large build, it would be the biggest weekly addition in barrels since such data became available in 1982.