PARIS (AP) -- A foul-smelling cloud of gas from a chemical factory has spread across parts of northern France, prompting scores of overnight calls to emergency services from fearful residents.

France's Interior Ministry released a statement Tuesday saying the gas, mercaptan, is harmless but because of prevailing winds has spread more than 100 kilometers (60 miles), into the Paris region. Among other uses, mercaptan is added to municipal gas to alert people of leaks.

The factory in the northern city of Rouen is owned by Lubrizol, a subsidiary of investor Warren Buffett's Berkshire Hathaway.

"Bearing in mind the lack of danger, residents of the areas concerned are asked not to call emergency services," the Interior Ministry said.