Government spokesman Damantang Albert Camara said the virus was found in tests conducted at a laboratory in Lyon, France.
A health ministry statement announced that 80 cases, including 59 deaths, had been reported, most of them in three southern prefectures near neighbouring Sierra Leone and Liberia.
There is no known cure or vaccine for the highly contagious virus, which is spread by close personal contact with people who are infected. Symptoms include internal and external bleeding, diarrhoea and vomiting.
A team including the health minister had been dispatched to the region, Mr Camara said, and Médecins Sans Frontières have set up an isolation unit in Gueckedou to try to stop the disease from spreading.
Dr Mohamed Ag Ayoya, country representative for Unicef, said in a statement yesterday that three children had died in the outbreak.
He added: “In Guinea, a country with a weak medical infrastructure, an outbreak like this can be devastating.”
Previous Ebola outbreaks have been reported in Congo and Uganda, most recently in 2012.
The only prior case of a human contracting the virus in West Africa came in 1994, when a scientist fell ill while responding to Ebola cases among chimpanzees in a national park in Ivory Coast, said Dr Esther Sterk, tropical disease adviser for Médecins Sans Frontières. The scientist eventually recovered.
Dr Sterk, who is coordinating the medical organisation’s response from Geneva, said it had confirmed 49 cases, including 29 deaths. Samples from six victims had been linked to Ebola, she said, though it was “quite likely” the others also contracted the virus.
“We see that a lot of people that died, they were all linked, meaning they have been in contact with each other,” she said. “That is very typical for Ebola outbreaks.
“We see that there is a transmission chain in families.”
Officials have not been able to determine how Ebola was introduced, although that can result from contact with an infected animal such as a bat or a monkey. Among humans the disease is transmitted through bodily fluids.
Officials have also been unable to determine the sub-type of Ebola, which would give them a better idea of the fatality rate, Dr Sterk said. The fatality rate for Ebola can range from 25 to 90 per cent.
Dr Sterk said there were concerns the disease could spread to neighbouring West African countries Sierra Leone and Liberia.
The health ministry said in a statement that one of the positive cases had travelled to Liberia.
“There’s definitely a risk but it all depends on the movement of the people,” Dr Sterk said.