No official reason was given Monday after President Ernest Bai Koroma did not join other government officials in leaving the country and he did not report to work.
His absence prompted rumors about his health to swirl online, and a government spokesman declined to address them.
Koroma is scheduled to attend the U.N. General Assembly in New York later this month and to meet with members of Sierra Leone's diaspora community in the United states.
The 59-year-old president was easily re-elected to a second term last November.
Earlier this month, though, authorities arrested six army soldiers and accused them of attempting a mutiny.