BELGIAN authorities morning stopped a bus travelling to Brussels from northern France and arrested three people after a passenger overheard them discussing a possible 'terrorist' plot, the local public prosecution office said. "Every time we get a notification like that we take it very seriously and we don't want to take any risk," a spokesperson at the Ghent prosecution office told Reuters, adding that police were currently checking the bus, its 46 passengers and their luggage. She declined to disclose any details on the suspects as well as on the content of their conversation. Belgium is on heightened alert after…