LONDON (Reuters) - Oil hovered below a three-year high near $70 a barrel on Monday on signs that production cuts by OPEC and Russia are tightening supplies, but analysts warned of “red flags” due to surging U.S. production. International benchmark Brent crude futures LCOc1 were trading 18 cents lower at $69.69 by 1004 GMT, having risen above $70 earlier in the session. U.S. energy companies added 10 oil rigs in the week to Jan. 12, taking the number to 752, energy service firm Baker Hughes (GE.