Two children have died from diarrhoea caused by an acute water shortage after the devastating cyclone in Bangladesh, local media reported today.
The deaths came in the hard-hit district of Patuakhali, Dhaka's Daily Star newspaper reported.
UN officials said the risk of waterborne diseases was a major concern as relief efforts began to provide supplies to thousands left homeless by Cyclone Sidr.
Official estimates suggested the number of fatalities from the deadliest cyclone to hit Bangladesh in a decade was at least 3,100.
"We are concerned about diarrhoea," Renata Dessallien, the most senior UN official in Bangladesh told the Associated Press. "There is no question this will be a problem."
She said water usually becomes contaminated by diarrhoea-causing bacteria after floods and cyclones. In the wake of last week's cyclone, many drinking wells have been destroyed.
"But I understand that the health ministry has a stock of medicines and the most important thing now is to get the supplies to the affected areas," she said.
Relief workers were scrambling to get enough supplies to survivors as ever-growing crowds of people struggled to get help. Fights broke out in some relief camps.
In Purba Saralia, nearly 2,000 people descended on a government-run relief camp hurriedly set up in a firehouse, where officials had food for only 1,200.
"This is a crisis. I don't have enough food and we have no work," said Lal Mia, a farmer waiting in line.
A few miles away, in the village of Basal Bar, fights broke out as thousands more people waited for rice at a food distribution centre up by a local aid group.
Food, fresh water and temporary shelter had still not reached many of the exhausted survivors six days after the cyclone hit Bangladesh's south-western coast last Thursday.
"At this time we will welcome support from the international community," the Bangladesh foreign ministry said. "We are doing as best as we can do ourselves."
About £58m in aid has been promised to Bangladesh so far, but items such as tents, rice and water have been slow to reach most survivors.
"The problem is that aid workers need hours to reach these remote areas. Poor communications are also hampering our work," said Anwarul Huq, a spokesman for the Bangladesh rural advancement committee, the country's largest non-profit development organisation.
In many places, aid workers had to clear fallen trees and debris to get to survivors, and rescuers were also facing a shortage of boats, said Huq.
Nearly 4 million people have been affected by the cyclone, which destroyed 458,804 houses. Another 665,529 houses were partially damaged, the ministry said.
Local media reports said more than 4,000 people may have been killed.