Britain promised the country £5 million in fresh aid ti help victims of the flood.
The disaster began on Monday when heavy rains hit the city and the partial collapse of a hillside triggered mudslides, engulfing homes and wreaking destruction.
“Today we are counting more than 400 people dead,” the secretary-general of the International Federation of Red Cross and Red Crescent societies, Elhadj As Sy, told reporters in Geneva.
Citizens and experts alike have questioned why the government has not done more to tackle illegal construction and deforestation on the outskirts of the overcrowded capital of Freetown.
An unofficial morgue estimate had previously put the toll at around 400 dead, but the figure had not been officially confirmed until Friday.
More than 300 victims were buried on Thursday in a ceremony in the nearby town of Waterloo, laid to rest alongside victims of the country’s last crisis, Ebola. Around a third of them were children.
Sy said the government of the west African country was facing a crisis “way beyond (its) capacity” and appealed to the international community to significantly ramp up its support.
The displaced are still sleeping outside “because there are not enough shelters for everybody,” he said.
Britain meanwhile announced £5 million ($6.45 million) in funding for several charities working on the ground, targeting children’s bedding and clothing and clean water and sanitation for all victims, as well as medical supplies.
“Our new support will provide basic life-saving supplies like food, water, shelter and clothing to people who have lost everything. The international community must follow our lead and step up to the plate,” said Britain’s International Development Secretary Priti Patel.
The Red Cross said it will launch an emergency funding appeal later on Friday, while China has pledged $1 million, Togo $500,000, and Israel and several west African nations have contributed food and cash.
The Red Cross has warned that smaller mudslides have occurred since Monday in eastern Freetown and in Sierra Leone’s second city of Bo, with the rainy season far from over.
So far evacuations have been voluntary from affected areas, which Sy said was “best practice” “Coming by force in the middle of hardship may not be the best way,” he added.
Jens Laerke, spokesman for the UN Office for the Coordination of Humanitarian Affairs in Geneva, told reporters the toll “may rise” noting the number of people still missing.