The World Health Organization has said disease has broken out in Pakistani-administered Kashmir among survivors of last month's earthquake.
WHO officials said they have found hundreds of cases of acute diarrhoea in the tent camps, which were established in and around the city of Muzaffarabad.
Doctors are investigating whether or not the cases were caused by cholera. Aid workers are now urgently trying to improve water supplies and sanitation at the cramped refugee camps.
The World Health Organisations' representative in Pakistan, Dr Khalid Bile, says the first cases were registered two days ago.
The UN has repeatedly warned it is racing against time to prevent a second wave of deaths from disease, cold and hunger after the 8 October disaster.
The 7.6-magnitude earthquake is confirmed to have killed 73,000 people in Pakistan and more than 1,300 in India. However humanitarian groups estimate the toll could be as high as 86,000 in Pakistan.
