By Karolin Schaps
LONDON (Reuters) - Oil prices fell on Wednesday after an unexpected rise in U.S. crude stocks, adding to a picture of global oversupply that has dragged down values over the past year.
Industry data released on Tuesday by the American Petroleum Institute (API) showed crude inventories at the Cushing, Oklahoma hub rose 2.3 million barrels last week, compared with analyst expectations for a decrease of the same volume.
"The U.S. crude oil stocks build reported by the API last night is weighing on prices," said Tamas Varga, analyst at London brokerage PVM Oil Associates.
U.S. crude held above $50 a barrel, trading down 71 cents at $50.15 at 0832 GMT.
The August contract, which expired on Tuesday, settled at $50.36 a barrel on its last day of trade, after slipping as low as $49.77 during the session.
Brent crude was down 62 cents at $56.42 a barrel.
U.S. government crude stocks data to be released by the Energy Information Administration (EIA) at 1430 GMT on Wednesday is expected to shed further light on the build-up in inventories.
A slightly weaker dollar capped losses in the crude market by making it cheaper for investors holding other currencies to purchase oil contracts.
The dollar was down 0.02 percent against a basket of global currencies.
The global supply glut is also taking its toll on the products market. China's exports of diesel will reach their highest since at least 1999 in August as its local market cannot absorb high output from refineries, sources said.
OPEC kingpin Saudi Arabia has also been stepping up exports of diesel.
(Additional reporting by Jacob Gronholt-Pedersen in Singapore; Editing by Dale Hudson)
