Heavy snow disrupted air and rail travel in northern Europe today, halting flights at London's main airport and bringing traffic in the British capital almost to a standstill, Reuters reported. Tens of thousands of commuters were advised not to attempt the journey into work in London, experiencing some of its worst snow in almost 20 years. Buses were taken off the roads and hundreds of schools were closed across the country, leaving children to play and build snowmen in parks and gardens. All flights in and out of Heathrow, a major international hub, were cancelled for a period before a limited service resumed with long delays and cancellations. One of its two runways was closed. . Weather experts said southeast England was experiencing some of its worst snow since the early 1990s. The international rail operator Eurostar also reported delays due to snow in Britain, France and Belgium. In France, traffic jams were recorded on roads leading into the capital during the rush hour and the Paris transport authority said many buses had to be cancelled. So far, this winter has been Britain's coldest in more than a decade and forecasters expect the cold weather to continue for several more days with freezing winds blowing in from Russia.