UPDATE 7-Oil pulled lower by gasoline sell-off

* Gasoline futures slump over 3 percent

* Nigerian rebels attack oil pipeline

* Weak dollar, rising equity markets support

(Recasts, update prices, details)

By Richard Valdmanis

NEW YORK, June 19 (Reuters) - Oil prices fell a dollar on Friday, pulled lower by a sell-off in the gasoline market as dealers bet there would ample fuel supply in the United States to meet demand from summer vacationers.

U.S. crude CLc1 fell $1.00 to $70.37 a barrel by 1635 GMT, led by a nearly 7-cent per gallon drop in gasoline futures RBc1. Brent crude LCOc1 fell 97 cents to $70.09 a barrel.

"Gasoline is under siege here, with the supply build after production rose last week," said Andy Lebow, broker at MF Global in New York.

U.S. gasoline supplies rose unexpectedly last week as refiners boosted output to prepare for an expected seasonal uptick in demand, according to government data issued Wednesday.