FARGO (AP) - After suspecting a sugar company, officials now say they may never know what caused a strong skunk-like smell to waft through this city and as far south as Wahpeton.

The Minnesota Pollution Control Agency said Wednesday night that the stench had been tracked to a lagoon at American Crystal Sugar Co. But company officials said their plant does not generate that type of odor.

A combination of factors, including odors from several sites, might have been involved, officials said Thursday. "I don't know if we'll ever be able to identify exactly what caused it," said Dan Olson, a spokesman for the MPCA.

Windy conditions might have combined odors from a number of locations, including the American Crystal lagoon and the nearby city of Moorhead compost site, Olson said.

American Crystal is confident it wasn't responsible for the odor, spokesman Jeff Schweitzer said. Moorhead's compost site produces an earthy odor that is nothing like Wednesday's stink, said Chad Martin, city operations director.