LONDON (AFP) - World oil prices fell Friday as traders awaited news of an expected economic slowdown in top energy consumer the United States. New Yorks main contract, light sweet crude for delivery in September, weakened 66 cents to 77.70 dollars a barrel. Brent North Sea crude for September retreated 63 cents to 76.96 dollars in early afternoon London deals. Later Friday, at 1230 GMT, the US government will publish its latest economic growth estimate for the second quarter, a key report that is widely expected to show the recovery is losing pace. Analysts expect gross domestic product (GDP) growth to slow to 2.5 percent in the second quarter from 2.7 percent in the first three months of 2010. The second-quarter GDP figure due out today from the Commerce Department will be eagerly watched as it should provide clues about the general health of the US economy, said PVM oil analyst Tamas Varga. The US economy emerged in the middle of last year from a brutal recession that struck in late 2007 but growth has eased, with some analysts worrying about a double-dip recession.