In Bolivia, the worst snow storms in the last 20 years, have left thousands of people stranded. The snow took farmers and tourists by surprise in the usually dry highlands of Potosi, a vast area in the south-west of the country. Farmers have lost their crops and more than 50,000 people are without food, after their farmlands were covered by a thick layer of snow. Roads remain closed and rescue efforts have been hampered by poor weather. The Bolivian government has appealed for help from neighbouring countries. Reports say, giving the vastness and isolation of the territory affected, it will be very difficult to clear up the roads soon.