* API reports U.S. crude inventories fall 8.1 mln barrels
* OPEC production up 393,000 bpd in June led by Libya, Nigeria
* Saudi to cut Aug oil exports to lowest level this year - source
* U.S. 2018 oil production outlook slightly revised downward - EIA (Adds OPEC production, updates prices)
LONDON, July 12 (Reuters) - Oil rose above $48 a barrel on Wednesday in response to a fall in U.S. fuel inventories and a cut in the U.S. government's forecast for crude output and despite OPEC suggesting the oil market will see a surplus next year.
U.S. crude inventories fell by 8.1 million barrels, industry group the American Petroleum Institute said on Tuesday, much more than the forecast.
Official inventory data from the Energy Information Administration is due at 1430 GMT.
Brent crude, the global benchmark, was up 62 cents, at $48.14 a barrel by 1130 GMT. U.S. crude gained 67 cents to $45.71.
"While further upside could be expected in the short term amid the speculations of a cut in U.S production, gains may be limited by the firm oversupply dynamics of the markets," FXTM analyst Lukman Otunuga said.
The U.S. crude stocks drop will raise hopes that a long-awaited market rebalancing is under way. A supply glut has stuck around for three years, despite an OPEC-led output cut in 2017, keeping oil at less than half its price of mid-2014.
Also supporting prices, the EIA said on Tuesday it expected U.S. crude oil production to rise by less than previously forecast next year due to a lower price outlook.
The lower 2018 forecast of 9.9 million barrels per day will ease concerns that the OPEC-led supply cut will lead to a flood of competing U.S. shale supplies, swamping the OPEC effort.
Still, output of 9.9 million bpd would be a record for U.S. production.
The supply cut led by the Organization of the Petroleum Exporting Countries has lent prices some support, but in recent weeks rising output from Libya and Nigeria - OPEC members exempt from the deal - has pushed supply higher.
In its monthly report, OPEC said its oil output rose by 393,000 bpd in June to 32.611 million bpd led by a rebound in Nigeria and Libya, plus extra barrels from Saudi Arabia and Iraq.
A Saudi industry source said on Wednesday that Riyadh planned to reduce shipments in August by more than 600,000 bpd, taking exports for that month to their lowest level this year, to balance a seasonal rise in domestic use.
OPEC forecast the world will need 32.20 million barrels per day (bpd) of crude from its members next year, down 60,000 bpd from this year. (Additional reporting by Ahmad Ghaddar in London and Henning Gloystein in Singapore; editing by Jane Merriman and Jason Neely)