French stench hits southern England after gas leak The offending agent on this occasion was a cloud of mercaptan gas, the "stenching agent" added to odourless municipal gas used in ovens and heating systems. Tony Ennis, Technical Director at Haztech Consultants Ltd, explained: "The material is one of a group known as Mercaptans - many of which are extremely smelly. Natural gas itself has no smell and the odour is added to make people aware of any gas leakage as a safety measure. Kent Fire and Rescue Service told people in the south of the county to keep doors and windows closed, after calls came in from Maidstone, Ashford, Dover and Folkestone. In London, the fire service reported on Twitter that it had received 38 calls to "gas incidents" by midmorning, five times higher than the whole of Monday, and signed off the message with the hashtag "#mondieu." A West Sussex Fire and Rescue Service spokesman asked people not to report the smell unless there were "other genuine reasons to suspect a gas leak" such as road works, due to the volume of calls. Residents of Maidstone reported "panic" on the High Street during the morning as confusion reigned over the malodorous stench. One man told the Telegraph: "Everyone thought it was a gas leak here. People were terrified something would happen. Then we saw it on the news and realised it had come from France. The Health Protection Agency issued a statement insisting that the gas would have dissipated so much on its journey of at least 100km from France that it did not pose any threat. A spokesman said: "It is an unpleasant odour which may cause some people to feel slightly nauseous but it will dispel naturally." In France, the incident caused more of a stink as more than 10,000 people jammed emergency phone lines overnight complaining of headaches and nausea. The Paris police department issued a statement saying the gas posed no health risks but warned that it smelled like a mixture of "sweat, garlic and rotten eggs." Ecology minister Delphine Batho cut short an official trip to Berlin to go to the site where the leak began on Monday, and regional authorities cancelled a French Cup football tie between Rouen and Marseille scheduled for this evening, fearing the possibility of having to evacuate thousands of fans from the site. The plant, which makes additives for industrial lubricants and paint, is owned by Lubrizol, a subsidiary of investor Warren Buffett's Berkshire Hathaway. Production was shut down and executives hoped to have the leaked plugged by Tuesday evening.