Thousands of children have been killed in the category-five storm and one charity worker said two out of every five corpses she had seen were youngsters.
Lynette Lim, of Save the Children, said: 'We are witnessing the complete devastation of a city. In Tacloban everything is flattened. Bodies litter the street, many, many of which are children. From what I saw, two out of every five bodies was that of a child.
Children are particularly vulnerable in disasters. We fear for how many children have been washed away in floods, crushed under falling buildings and injured by flying debris.
'Many are separated from their families amid the devastation, and all are in desperate need of food, water and shelter.'
In the worst-hit areas, 235mph winds created 20ft waves that are thought to have killed between 10,000 and 15,000 and left 500,000 homeless after their houses were reduced to splinters.
Super-typhoon Haiyan struck with such force on Friday that entire villages were flattened, ships were swept inland and corpses were left hanging from trees.