The group claimed responsibility for the cyberattacks in a series of Twitter posts using the hashtag #FreeSenegal used by campaigners alleging political repression in Senegal.
The attacks come at a time of heightened political tensions in Senegal. One person was killed on Friday in the latest violent standoff between state security forces and opposition supporters.
In a statement about the cyberattacks in the early hours of Saturday, government spokesperson Abdou Karim Fofana said all efforts were being made to bring the sites back online.
As of Saturday evening, the presidency's site was online but other official websites still appeared to be offline, including the government and finance ministry sites.
DDoS attacks work by directing high volumes of internet traffic towards targeted servers in a bid to knock them offline.
On its Twitter account, the so-called Mysterious Team group says its members are "cyber warriors from Bangladesh".
The group is little-known, but has carried out previous cyberattacks against the Ethiopian health ministry and Indian media, according to the European Repository of Cyber Incidents, an independent research consortium that analyses cyber incidents.
The connection between Bangladesh and Senegal was not clear. Contacted by Reuters about its reasons for targeting the Senegalese authorities, a representative of Mysterious Team said "We are working for justice for Senegal innocent peoples."
The country has been shaken by more than two years of sometimes violent protests over a host of issues including fears among the opposition that Sall may seek a third term in office in the February 2024 election.
The opposition has also accused Sall's government of using the judicial machinery to target potential challengers such as popular politician Ousmane Sonko, who placed third in the 2019 presidential race. The authorities deny ongoing legal cases against Sonko are politically motivated.
On Saturday, a regional prosecutor said one 37-year-old man had been killed a day earlier during clashes between security forces and Sonko's supporters in the city of Kolda. The area was on the route of an ongoing march by Sonko back to the capital that he has urged his followers to join in a show of defiance.
Opposition coalition Yewwi Askan Wi said the authorities were responsible for the death, accusing police in a statement on Saturday of barricading the road of Sonko's convoy and provoking the violent encounter. The prosecutor said an investigation had been opened.
Reuters, the news and media division of Thomson Reuters, is the world's largest multimedia news provider, reaching billions of people worldwide every day.Go to: https://www.reuters.com/