Heavy gunfire has been heard in the centre of Guinea's capital, Conakry, while soldiers have been seen on the streets near the presidential palace.

It is not clear what is behind the shooting, and authorities in the West African country have not commented.

The district of Kaloum is reported to be deserted as terrified residents heed soldiers' orders to stay at home.

A senior government official told Reuters that President Alpha Condé was unharmed but gave no further details.

The only bridge connecting the mainland to the Kaloum peninsular, which houses most ministries and the presidential palace, had been sealed off and many soldiers, some heavily armed, were posted around the palace, a military source told Reuters.

There are unconfirmed reports that three soldiers have been killed.

Videos shared on social media show convoys of armoured vehicles and trucks carrying soldiers patrolling the streets, although these have not been verified.

President Condé was re-elected for a third term in office amid violent protests last year.