Several people have been killed in southern Guinea, according to local officials, in an outbreak of violence after the country's contested constitutional referendum.

The number killed in Nzerekore, the West African state's second-largest city, which borders Liberia, is unclear and the circumstances are sketchy.

UN Secretary General Antonio Guterres condemned the violence in Guinea and called on all sides to immediately show restraint, his spokesman Stephane Dujarric said.

The local government has said that three people were killed in unrest there, while a local doctor and the political opposition cited a figure of 15.

AFP was unable to independently confirm the figures.

City residents said that clashes have taken place in the city since Sunday -- the day of the referendum on changing the constitution.

Guinea's government has argued that a new constitution is needed to enshrine gender equality in the impoverished former French colony.

But critics fear the real motive is to allow President Alpha Conde, 82, to run for a third spell in office later this year.

At least 32 people were killed in months-long protests in the runup to Sunday's vote, according to an AFP tally.

On polling day itself, 14 people were killed in the capital Conakry, according to a figure provided by the political opposition that AFP was unable to confirm independently. The government has said that six people died in Conakry on Sunday.

Protesters confront the Guinean army in the streets in Conakry on March 22, 2020, during a constitutional referendum in the country
Protesters confront the Guinean army in the streets in Conakry on March 22, 2020, during a constitutional referendum in the country AFP / CELLOU BINANI

Nzerekore residents contacted by AFP reported violent incidents between religious and ethnic communities, including attacks on churches and mosques.

Authorities said one Protestant church had been burned down since Sunday, and a man was killed by unidentified individuals on the day of the vote.

Mohamed Ismael Traore, the governor of the Nzerekore region, said young men from a border village came to the city "armed to the teeth with weapons of war and charms to protect themselves from bullets".

A city resident who fled to the bush with her children during the attack said the assailants burned down a church, as well houses belonging to ethnic Guerze people.

"They killed three innocent members of my family," she said.

The total number of victims remains unclear, however.

Speaking on condition of anonymity, a Nzerekore doctor said he had counted 15 bodies in the hospital, including three which had been taken there on Tuesday morning.

A leading member of the political opposition in Nzerekore cited the same figure.

But Traore, the governor, told AFP the figure is false.

"It's not true, there are not 15 bodies, there are only three in the morgue," he said.

Traore added that a curfew had been imposed on Nzerekore residents on Tuesday.