Many are said to be suffering from an acute form of diarrhoea, known as Shighella, which can be life-threatening if not treated.

A BBC correspondent in the region says lack of food and water has aggravated the problem.

There is very little fresh water in the earthquake zone, because most wells, springs and water canals were shattered by the quake.

Injured wait for threatment in Faizabad hospital

The BBC correspondent says there is always concern about outbreaks of disease following natural disasters and the latest reports are being taken very seriously.

The international relief effort is being slowed down because there are still only four helicopters in service. Others which were promised have failed to arrive.

Pakistan has promised to station three helicopters in Afghanistan. It agreed to supply the helicopters after aid workers criticised Pakistani officials for demanding fuel, which was needed for aid deliveries.

Aid workers have said that food supplies are piling up in the northern Afghan town of Faizabad, and, with bad weather hampering the relief effort, they need helicopters and fuel to deliver them to the villages affected.

Isreali aid

Israel has sent a plane-load of blankets, tents and medicine to the quake survivors.

Israeli officials said the plane would travel first to Georgia, to deliver aid to people affected by fighting in Abkhazia.