Paris - Twitter and Facebook lit up this weekend when pranksters reported that an asteroid was hurtling toward France, prompting a humourless denial on Monday on the website of a national radio station. A house-sized rock was on track to crash into the southern city of Marseille on March 5, the fake reports, in French, said in widely-circulated tweets.The French government and NASA - abetted by the media - were trying to hide the bad news from the public to avoid panic, the authors of the tweets claimed.Like much spurious news circulating on social networks, these false reports contained a grain of truth.Earlier this month, NASA's Center for Near Earth Objects Studies at the Jet Propulsion Laboratory announced that an asteroid about 30m named TX68 would pass by our planet on the appointed day, perhaps as close as 17 000km.On an astronomical scale, that's a close shave.But there was absolutely no possibility, the US government scientists said, of an impact with mothership Earth. In fact, the asteroid was just as likely to fly by more than 14 million km away.According to French radio station France Info, the hoax started with French video gamers trying to start a "trending topic" - one of the most talked about topics of the day - on Twitter.They used the hashtag, or keyword, "#ImpactFrance," to fuel the rumour.TX68 AsteroidWhile they may not have reached their goal, the hoax gained enough tweets during the weekend to reach nearly one million pairs of eyeballs on Twitter.One user tweeted in English, presumably tongue in cheek: "I will leave France and go to Austria."Many others, referring to a research centre in the US state of Arizona, tweeted: "According to the Catalina Sky Survey, 2013 TX68 Asteroid may hit Earth on French territory."Some tweeted maps purportedly showing the asteroid's trajectory and the area of its expected impact - saying that the meteorite's residue would shower debris as far as north Africa.But here's the kicker: the TX68 will approach Earth again in 2017, and this time - according to NASA - there's a one-in-250 000,000 chance of a violent rendezvous. However, the possibility is "far too small to be of any real concern," NASA said reassuringly.