The UN says at first the full scale of the disaster was not understood

The UN's Office for the Co-ordination of Humanitarian Affairs (OCHA) now says the disaster is of a scale unknown in the history of the subcontinent.

Despite the assistance which poured into the region in the aftermath of the quake, each day reveals acute new needs, it says.

But the UN says it has received less than a quarter of the $550m it says it needs - much of it to cope during the emergency phase of the relief operation, now predicted to last several months.

As winter looms, the main needs are:

• Shelter - most importantly, winterised tents to protect hundreds of thousands of people, some in mountainous zones where temperatures may dip to -12C. Blankets and warm clothing are also needed

• Health care - more than three weeks after the quake, untreated wounds are becoming infected and fractures are worsening. Medics and supplies are needed to treat injuries, and to prevent the spread of illnesses brought on by the lack of hygiene and cold weather

• Food - this is likely to be a long-term requirement, as the earthquake wiped out food stocks and destroyed farms

• Clean water and sanitation.

The organisations listed below are among those working in the field. Click on the links to visit their websites and donate.

• Unicef

• UNHCR

• World Food Programme

• International Federation of the Red Cross

• International Committee of the Red Cross

• International Organization for Migration

• Kashmir International Relief Fund

• Disasters Emergency Committee (UK)