Prime Minister Lee Hsien Loong expressed his condolences and extended his sympathies to the families who lost loved ones in the earthquake that struck Sabah on Friday.
In a statement from the Prime Minister's Office, he said: "On behalf of all Singaporeans, the Prime Minister expresses his deepest condolences and sympathies to their families and loved ones. As we grieve over the loss of these young lives, we also take heart that they were striving to stretch their limits and take on new challenges.
"The Prime Minister also thanks all those who are working tirelessly in the search, rescue and recovery efforts - the Malaysian authorities, the search and rescue teams, the hospital staff, and all the officers and volunteers who are helping in one way or other in Sabah and Singapore."
Mr Lee has also declared Monday, Jun 8, will be a Day of National Remembrance.
State flags on all government buildings will be flown at half-mast.
One minute of silence will also be observed at the beginning of the day at all SEA Games venues.
Mr Lee added: "We hope that this collective expression of sympathy and support from all Singaporeans will give solace and comfort to the families and loved ones of the victims."
On Sunday, at 12.30pm, the Ministry of Education confirmed that the bodies of five more pupils and one teacher from the school were identified. Their Singapore adventure travel guide also died in the earthquake.
The pupils had been on a trek up Mount Kinabalu when a magnitude 6.6 earthquake struck.