Senegal closed its land border with Guinea on Saturday to try to prevent the spread of the Ebola virus, which Guinean authorities say is suspected of killing 70 people in what would be the deadliest outbreak in seven years.
The discovery of 11 people suspected to have died of Ebola in Sierra Leone and Liberia in recent days has stirred concern that one of the most lethal infectious diseases known to man could spread in a poor corner of West Africa, where health systems are ill-equipped to cope.
Senegal's Interior Ministry said it had closed the land border with Guinea in the southern region of Kolda and the southeastern region of Kedougou.
"The governors of these regions have taken all the necessary steps to implement this decision," it said in a statement published by the official APS state news agency.
A spokesman for Guinea's government said it had not received any official notification of Senegal's decision. The extent of the epidemic is being exaggerated and only 19 cases of Ebola have officially been confirmed by laboratory tests, he added.
"We've taken strict measures to stop this epidemic and there is no reason to panic," Damantang Albert Camara told Reuters.
Senegal announced on Friday it would introduce sanitary checks on flights between Dakar and the Guinean capital Conakry, where eight cases of Ebola have been confirmed, including one death.
West African foreign ministers said at a conference in Ivory Coast this week the Ebola outbreak posed a "threat to regional security".
If the 70 deaths to date are all confirmed as Ebola, it would be the most deadly epidemic since 187 people died in Luebo, in Congo's Kasai Orientale province, in 2007.
The vast majority of the cases in Guinea have been detected in the country's remote southeast, near the border with Sierra Leone and Liberia. It took authorities nearly six weeks to identify it as Ebola, allowing the virus to spread.
The arrival of the disease this week in the capital Conakry, where hundreds of thousands of people live tightly packed in rambling shanties, marked a sharp increase in the population at risk compared with the sparsely populated villages of the forested interior.
Sakoba Keita, head of the prevention division of Guinea's Health Ministry, said there was no cause for alarm in Conakry as the spread of Ebola could be tackled by simple sanitary steps such as regular hand washing and the quarantine of victims.
"There have been delays in applying certain measures in our health system," Keita told a news conference, noting six medical staff were among those killed by the disease. "From today, strict hygiene measures will be observed in our hospitals."
There is no vaccine and no known cure for Ebola, which initially induces fever, headaches, muscle pain and weakness. In its more acute phase, Ebola causes vomiting, diarrhea and external bleeding that carry the virus outside victims' bodies and threaten to infect anyone who touches them.
Ebola has killed more than 1,500 people since it was first recorded in 1976 in what is now Democratic Republic of Congo, but this is the first fatal outbreak in West Africa.
Guinea is deploying a mobile laboratory to the southern region of Gueckedou to speed up identification of the disease and to test samples from Sierra Leone and Liberia.