Oil fell on July 13 after the International Energy Agency (IEA) warned that a global supply glut threatened a price recovery and data showed an unexpected weekly gain in U.S. crude stocks.

The IEA, which advises industrialized nations on energy policies, said crude inventories kept rising last month and pushed floating storage to the highest level in seven years.

"[Stocks] are at such elevated levels, especially for products for which demand growth is slackening, that they remain a major dampener on oil prices," the Paris-based IEA said in its latest report.

Stocks of U.S. crude and refined products rose unexpectedly last week by 2.2 million barrels (MMbbl), data from the American Petroleum Institute, an industry group, showed late on July 12.

This provided further bearish impetus to the market a day after prices had risen 5%, giving investors a chance to lock in gains.

The U.S. government's Energy Information Administration (EIA) releases official weekly inventory data at 9:30 a.m. CT (14:30 GMT) on July 13.

Global benchmark Brent oil was down 74 cents at $47.73/bbl at 6:39 a.m. CT (11:39 GMT) after settling up $2.22, or 4.8%, in the previous session.

U.S. crude traded at $46.25/bbl, down 55 cents on close on July 12.

A further potentially bullish factor was removed when Nigerian oil workers agreed to suspend strike action that could have disrupted crude oil production.

Despite its bearish oil price outlook, the IEA also raised its forecasts for oil demand growth by 0.1 MMbbl/d to 1.4 MMbbl/d in 2016 and 1.3 MMbbl/d in 2017.

"Therefore any weakness based on the IEA report should be short-lived," said Tamas Varga, oil analyst at London brokerage PVM Oil Associates.

Credit Suisse raised its 2016 oil price forecasts on July 13. The bank forecast U.S. crude would average $43.59/bbl this year vs. $36.91 in its earlier forecast, and $55 for 2017, vs. $52.88 earlier.

Brent will average $44.53/bbl this year, up from $37.77, and average $56.25 in 2017, up from $54.25 earlier.