Gunfire was heard in the centre of the Guinean capital Conkary on Sunday morning and troops were seen on the streets, witnesses told AFP.
There was no immediate explanation for the incidents in Conakry’s Kaloum peninsula, where the presidency, various institutions and offices are located.
Authorities in the West African nation were not commenting on the situation.
Residents reached by telephone in Kaloum reported hearing sustained gunfire.
Speaking on condition of anonymity for their safety, they reported seeing a number of soldiers on the streets who called on residents to return to their homes and stay there.
Security forces can easily block access to Kaloum because of its geography.
Guinea is among the world’s poorest countries, despite its rich mineral resources, and has been beset by political instability for years.
For example, President Alpha Conde won a third presidential term in Guinea in a violently disputed election last October.
He ran after pushing through a new constitution in March 2020 which allowed him to sidestep the country’s two-term limit, provoking mass protests.
Dozens of people were killed during demonstrations, often in clashes with security forces. Hundreds were also arrested.
Conde, 83, was then proclaimed president on November 7 last year — despite complaints of electoral fraud from his main challenger Cellou Dalein Diallo and other opposition figures.
A former opposition activist himself, Conde became Guinea’s first democratically elected president in 2010 and won re-election in 2015 before doing so again last year.
Critics accuse him of veering towards authoritarianism, however.