French gas cloud causes stink across the South East In London, the fire service revealed in a tweet with the hashtag "#mondieu" that it had received 38 calls to "gas incidents" since mid-morning, five times higher than the previous day. Meanwhile the National Grid said its gas emergency phone line had received more than 100,000 calls - an "unprecedented number" - by 2pm, with just 8,000 to 10,000 usually expected in one day. Mother-of-four Jane Gillham, 45, from Eltham, south east London, said: "There was a bit of a whiff in the air. It wasn't very strong but I couldn't work out where it was coming from. I checked the hob a couple of times in case one of the switches was accidentally left on. It's amazing that the smell has travelled so far from France. Hastings resident Lucy Parker, 27, said: "I woke up and looked at my boyfriend and told him off for farting in the bed. He just looked at me and started blaming me, but then we realised the smell was completely overpowering and wasn't coming from either of us. It is totally disgusting and makes you wretch. Online wags were soon making a joke out of the malodorous pong. One tweeted: "Apparently if there is a rotten, gas smell in the South East today, don't worry. It's just France. Experts at the Health Protection Agency's Centre for Radiation, Chemical and Environmental Hazards in Oxfordshire were scrambled to investigate. But they established that the gas had dissipated so much in is journey from France that it was unlikely to cause harm. In a statement, the HPA said: "The smell drifting over Southern England today poses no risk to public health. The odour, which is similar to rotten eggs, has been noticed by people mainly in Kent, East and West Sussex and some parts of Surrey. It is caused by a particularly smelly chemical that is added to odourless natural gas to give that its characteristic smell. The chemical leaked from a factory in Rouen, France yesterday and has blown across the Channel overnight. It is not toxic and has also been diluted before entering the air over England, so people should be reassured it will cause no harm. It is an unpleasant odour which may cause some people to feel slightly nauseous but it will dispel naturally. Mercaptan is an additive used in municipal gas to alert people to leaks. In France, more than 10,000 people had jammed emergency phone lines overnight complaining of headaches and nausea. But France's ecology minister Delphine Batho, who cut short an official trip to Berlin to go to the site of the leak - which began on Monday - said there was no health risk. The Lubrizol plant, which makes additives for industrial lubricants and paint, shut down production and executives hoped to have the leaked plugged by later today. Regional authorities cancelled a French Cup tie between Rouen and Marseille scheduled for this evening, fearing the possibility of having to evacuate thousands of fans from the site.