Heavy monsoon rains have forced Sri Lanka's president to abandon a visit to areas affected by severe flooding which has displaced nearly 200,000 people and killed 18 others.
Mahinda Rajapaksa had to cancel his helicopter trip from Polonnaruwa in the east to the badly affected coastal city of Batticaloa 120km (75 miles) away.
The downpour is continuing after two weeks of rain in the centre and east.
The floods have inundated farmland and destroyed rice fields.
The eastern cities of Ampara and Batticaloa have been worst affected by the deluge, which has left some stretches of railway line under nearly a metre of water.
Officials in Ampara say the rainfall there since Saturday has been the highest ever recorded in such a short time.
"There is a shortage of food for children," a member of Sri Lanka's minority Muslim community in Ampara told BBC Tamil.
"In the morning we were forced to divide a single breakfast food parcel into four and give it to our four children.
"We have not got any help from the government. But the local people - especially the rich - have come forward and helped us... We are only getting something to eat because of their generosity."
A number of big reservoirs have burst their banks, destroying paddy fields in a major rice-growing area.
People in some remote areas have told the BBC they have seen no sign of aid agencies or government relief, and that some people in makeshift camps have been missing out on meals.
Those displaced by the floods have squeezed into 800 camps that have sprung up in school premises, many of which are surrounded by water. Some camps are themselves flooded, forcing people to go elsewhere to escape the water.
A deputy government minister, Mohammed Hizbullah, told the BBC the situation in the east coast town of Batticaloa was getting worse as night fell on Wednesday.
He said that 25 out of 200 makeshift camps for displaced people had themselves come under water and the armed forces were helping people get out to safer places.
Numerous towns and villages were flooded with no road access and the authorities were getting calls for help from villagers whom they were unable to reach, Mr Hizbullah said.
People in Batticaloa district told the BBC Tamil service they had done their best to stay in their villages, but had been forced to flee in the end.
"We tried staying in the houses, but with continuous rains it's impossible," one woman said. "There was 5ft (1.5m) of water inside the house."
She and many others had been taken to safety in makeshift camps by tractor.
"All our clothes are wet and we don't have spare clothes to change into. We have come here leaving everything back home," another man said.
The air force has helped evacuate people and drop food supplies to some cut-off communities.
The government has made an emergency appeal for ordinary people's help in sending dry rations, mattresses and bottled water.
Clean water and food supplies have been sent by official and international agencies to the worst-hit areas.
But the deputy disaster management minister Duleep Wijesekara said some places, such as Muttur, have been difficult to reach.
"I boarded a high-speed navy boat to get there [to Muttur], but due to the huge waves we had to turn back after sailing for about 15km. After that we had to send food in by air," he added.
The floods bring a risk of disease, including the mosquito-borne dengue fever, which even in normal times is a severe problem in the country.
The health ministry and relief organisations are trying to supply hygiene kits and raise people's awareness of health hazards.