MEXICO CITY, Sept 11 (Reuters) - Mexican industrial output slipped in July, underscoring weak growth that could push policymakers to further lower interest rates. July industrial activity fell a seasonally adjusted 0.08 percent versus June, compared with forecasts in a Reuters poll for an increase of 0.30 percent and an upwardly revised 0.2 increase in June, the national statistics agency said on Wednesday. Weak U.S. demand for Mexican exports and a slump in construction spurred the first contraction in economic growth in four years during the second quarter. That pushed the central bank to unexpectedly cut interest rates last week. Factory output rose 0.44 percent in July compared to the prior month, while construction fell 1.12 percent compared to June. Mining and utilities rose on a monthly basis. Solid U.S. demand supported Mexico amid sluggish global growth last year, allowing Latin America's No. 2 economy to notch 3.8 percent growth in 2012, but the current slump pushed the government to forecast a 1.8 percent expansion this year. Industrial output fell 0.5 percent in July from a year earlier, better than expectations for a 0.90 percent drop and a less steep slump from June's upwardly revised 2.17 percent slump. The statistics institute last month revised its methodology to use 2008 as the base year, replacing the previous series based on 2003.