WASHINGTON, May 15(Reuters) - U.S. factory production accelerated in April as motor vehicle output surged, suggesting underlying strength in manufacturing, though supply disruptions from the war with Iran are casting a shadow over the sector.

Manufacturing output increased 0.6% last month after an upwardly revised 0.1% gain in March, the Federal Reserve said on Friday. Economists polled by Reuters had forecast production at factories rebounding 0.2% after a previously reported 0.1% dip in March. Production at factories advanced 1.3% on a year-over-year basis in April. Motor vehicle output increased 3.7%.