Hope is dwindling for the tourists missing after the apocalyptic floods in Nepal yesterday - as rescuers battle near-impossible conditions to reach survivors.Thousands are feared dead after a churning wall of mud, rock and freezing water bulldozed down the Rasuwa valley, crumpling concrete and washing away entire villages in disaster-movie scenes.Desperate images have emerged from the receding waters of villagers battling to escape swirling cesspits of debris and picking through rubble for survival essentials.Other footage, too graphic to publish, shows remains being pulled from the river banks - the victims' bodies severely injured by the seismic force of the water.The US Geological Survey has now said the torrent was caused by a 'glacial collapse' - thought to have seen a 2,000ft mass of ice break away - causing 'catastrophic impacts downstream'.Rescuers said last night 157 bodies had been pulled from the water and rubble, but the death toll was expected to climb significantly. One emergency worker said it would take hours to reach stricken areas because of the five-foot-deep sediment blocking roads.More than 300 of those missing were tourists, who had been visiting for the area for the hiking and religious pilgrimages for which it is famed. A village that was half washed away by the torrent of water in Nepal Military personnel rescue a man coated in mud from the floodwater The ferocious floods carved a wide scar down the course of the Trishulu River Police officers carry an elderly lady to safety on Wednesday afternoon Survivors pushing through debris-strewn water to salvage essentialsFamilies of the 33 Britons, including a schoolgirl, who were in the area but are now uncontactable have told the Daily Mail of their anguished wait for information. Prime Minister Andy Burnham has vowed to do 'everything we can' to support Britons caught up in the nightmare.Also among the missing were 133 Indians, 53 Ukrainians, 47 Americans, 34 Australians, 24 Canadians and eight South Koreans.A 13-year-old British girl and her parents are believed to have been among a tour party of 17 trekkers crossing the Nepal-China border at precisely the moment disaster struck.One neighbour told the Mail last night: 'They're a wonderful family. We're devastated by this news and are praying that they'll be OK.'Britons aged 13 to 65 who were on the nine-day trek to Mount Kailash - a sacred site for Hindus and Buddhists.Ram Kumar Adhikari, who runs Alpine Eco Trek, which organised the tour, said the group was last heard from at the Gyirong border crossing at 8.40am Nepal time.Some 15 minutes later, a wave of mud and rubble swept down the valley and engulfed the crossing. Mala Patel, 60, from Coventry, who is uncontactable after going on an organised religious trip to the Nepal-Tibet border Residents gaze over buildings submerged in mud as the sun rises on Thursday morning A local trudges through deep sludge in Devighat, in Nepal's Nuwakot district, on Thursday morning Bridges were destroyed and trees uprooted, causing damage that will take years to undo A woman grieves outside a hospital in Trishuli Bazar, where hundreds are feared to have died