UPDATE 1-Mexico's GAP posts 18 pct drop in net profit

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MEXICO CITY Oct 27 (Reuters) - Mexican airport operator Grupo Aeroportuario del Pacifico on Tuesday posted an 18 percent fall in third-quarter net profit as it continues to suffer from the effects of the swine flu epidemic earlier this year and a slow economy.

The company, known as GAP (GAPB.MX) (PAC.N), said it earned 314 million pesos ($23 million) from July to September compared with 383 million pesos in the year-ago period.

Quarterly revenue dropped to 791 million pesos from 831 million pesos from a year ago. Passengers in the period fell nearly 10 percent year-over-year.

GAP shares ended off 3.04 percent to 35.35 pesos on Tuesday.

($1=13.5035 pesos at end-Sept) (Reporting by Noel Randewich, Cyntia Barrera Diaz)