UN spokesman Stephane Dujarric said in New York that the UN country team was supporting national authorities in rescue operations.
Freetown: Sierra Leone began a weeklong period of national mourning on Wednesday as it emerged that 105 children were killed by the mudslides and torrential flooding that have left 600 people still missing in Freetown, in one of the worst natural disasters to hit the country.
President Ernest Bai Koroma said flags would fly at half-mast after calling the humanitarian challenge ahead "overwhelming" and seeking urgent help after visiting the devastated hilltop community of Regent on Tuesday.
Officials at Freetown's central morgue said Wednesday that 105 of the more than 300 officially dead were children, and burials began on Tuesday for some of the bodies too mutilated to identify. An independent but unofficial morgue estimate put the toll at 400 dead.
The government of Sierra Leone, one of the poorest countries in the world, has promised relief for what the Red Cross said is more than 3,000 people left homeless, opening an emergency response centre in Regent and registration centres to count those left on the streets.
The United Nations said Tuesday that it was evaluating humanitarian needs in country, while the first Israeli aid packages were sent from Senegal and the World Food Programme (WFP) distributed two-week rations of rice, pulses and cooking oil to 7,500 people.
UN spokesman Stephane Dujarric said in New York that the UN country team was "supporting national authorities in rescue operations, helping evacuate residents, providing medical assistance to the injured, registering survivors, and providing food rations, water and dignity kits to those affected."
Several aid organisations warned that the rainy season was not yet over and that more flooding could arrive at any moment in the west African coastal city of around a million people.
- From shock to anger -
Speaking to AFP at the mortuary at the Connaught Hospital, technician Mohamed Sinneh Kamara said his team lacked equipment to process and identify the bodies that are still piling up.
"We have logistical constraints including a lack of gloves, PPE (personal protective equipment) and rain boots," he said as families gathered to identify their loved ones' bodies.
Mabinty Sesay's family had gone to Regent for an all-night prayer session when their church was buried in the mudslide. "I have lost 13 of my family members but was only able to identify two," she told AFP at the morgue.
One woman collapsed after seeing her husband's dead body among the piles of corpses, amid a powerful stench of decomposing flesh.
Adele Fox, national health coordinator for Sierra Leone at the charity Concern Worldwide, told AFP that the search for bodies continued but that survivors were facing difficult conditions.
"There is basic need for food, water, sanitation equipment and medical assistance. Since it is still the rainy season, further flooding is also a possibility," she said.
The sentiment among those in the disaster areas had shifted from shock and grief to anger at what is an annual problem in Freetown, though never before on this scale.
"There is some frustration over the regularity of flooding and destruction during the rainy season and its effects," Fox said.
The British charity Oxfam said it was trying to prevent a cholera outbreak by distributing clean water and hygiene kits to 2,000 households.
"These are some of the poorest areas in Freetown. Water and sanitation in homes is at best very basic, but at worst nonexistent. Overcrowding is a serious health risk and a potential breeding ground for the spread of disease," said Daniel Byrne, part of the Oxfam team in the city.
- Wake-up call? -
There was growing concern that the warning signs had been missed in a city where illegal construction on precarious ground is common, and President Koroma said in a statement released by his office that "relocation and opening up of a new settlement around the Freetown peninsula" would be considered.
Many homes are now without a water supply due to damage to a reservoir near Regent, according to the Guma Valley Water Company.
An official with Freetown's city council said that 150 burials took place on Tuesday evening and that many victims would be laid to rest in graves alongside those of the country's last humanitarian disaster, the Ebola crisis, in nearby Waterloo.
But a government statement said the burials of unidentified bodies would take place on Thursday and Friday.
Guinean President Alpha Conde visited to express his solidarity with Sierra Leone on Tuesday and was galvanising other west African nations to provide aid, his aide Naby Youssouf Kiridi Bangoura told AFP.
Three days of torrential rain culminated on Monday in the Regent mudslide and torrential flooding elsewhere in the city, one of the world's wettest urban areas.
Freetown is hit each year by flooding during several months of rain, and in 2015 bad weather killed 10 people and left thousands homeless.
Sierra Leone ranked 179th out of 188 countries on the UN Development Programme's 2016 Human Development Index, a basket of data combining life expectancy, education and income and other factors.