U.S. industrial output fell in September for the second month in a row, the Federal Reserve said Thursday in a report underscoring the fragility of the manufacturing sector in the uneven U.S. recovery.

The Fed said output at U.S. factories, mines and utilities edged down by 0.1 percent in September after dropping by 0.3 percent in August. Manufacturing output, the largest segment in the report, dropped by 0.3 percent last month, after declining 0.2 percent the previous month.

Businesses also ran at a slower pace last month, operating at 75.9 percent of total capacity, the lowestt, the Fed said the effects from tropical storms on oil and gas extraction and petroleum refining around the Gulf of Mexico helped lead to reductions in both capacity use and industrial production.

Still, September's decline in industrial output was unexpected. Economists in a Reuters poll forecast, on average, that industrial production would actually inch up 0.1 percent.

Production at motor vehicle and parts plants fell off 1.6 percent in September, the second straight monthly decline, while motor vehicle assemblies eased to a 12.72 million annual pace in September from a 12.91 million pace.

Output excluding autos and parts was unchanged after dropping by 0.3 percent in August.