President Koroma recalled that in early 2014 when the country was hit by Ebola outbreak, which later devastated his country, China was the first country to send in support to fight the virus together with Sierra Leone.
With more rain forecast for the coming week, further mudslides are possible.
More than 600 people remain missing and search operations are hampered by the continuous rain, the United Nations said.
"We all share the agony which has befallen the nation", President Ernest Bai Koroma told mourners at the cemetery. The Office of National Security warned people of the danger from the newly opened crack on the side of a mountain and urged residents to evacuate.
An unofficial morgue estimate had previously put the toll at around 400 dead, but the figure had not been confirmed until Friday.
"People are going through a complicated grieving process. first Ebola, now the mudslides", she told AFP. The disaster began Sunday night, following three days of torrential rain. The capital also is plagued by unregulated construction in hilltop areas.
Charge D'Affaires WANG Xinmin, on behalf of the Chinese government and people expresses deep condolences to the people who lost their lives and sympathies to those affected by the disaster as well as the bereaved family members.
"The scale of the damage is unprecedented", UN Children's Fund (UNICEF) Representative, Hamid Ibrahim, said in a statement.
In recent years, trees have been cut down from the Western peninsular forest on Freetown's limits, with everything from shacks to mansions springing up haphazardly on the slopes.
Identifying deficiencies in waste management, preventing deforestation, urban planning and the provision of decent housing, Hitchen said "a problem of politics" meant that the city's drains were blocked and dump sites were full.
The government has said that in the light of the catastrophe, relocation and a new settlement around the Freetown peninsula would be considered, but similar measures have failed in the past as people seek to live close to the city centre for work. The country is a former British colony.
Sy said the government of the west African country was facing a crisis "way beyond (its) capacity" and appealed to the global community to significantly ramp up its support.