One person has been reported injured on Tuesday, in Abuja, when policemen fired teargas canisters at protesters.
The wounded person has since been taken to a clinic at the Federal Secretariat complex, a few kilometres from the scene of the incident. The extent of his injuries could not be immediately ascertained.
The group were having their sit-out at the Millennium Park opposite the Unity Fountain, Maitama, Abuja when the armed policemen fired tear gas canisters to disperse them.
The participants, however, braved the assault and continued with their meeting for about an hour.
The protesters, who are members of about four civil society organisations, are demanding that Buhari should return to the country or resign if he was incapacitated.