Oil slips as rising U.S. output offsets OPEC-led cuts

By Christopher Johnson LONDON (Reuters) - Oil prices slipped on Tuesday as rising U.S. drilling activity undermined efforts by OPEC and other producers to cut output in a move to prop up the market. Brent crude oil was down 20 cents a barrel at $55.03 by 0900 GMT. U.S. light crude was down 30 cents a barrel at $52.33.