Two new cases of Ebola have emerged in Nigeria and, they are outside the group of caregivers who treated an airline passenger who arrived with Ebola and died, Health Minister Onyebuchi Chukwu said Friday.

The two are spouses of a man and woman who had direct contact with Liberian-American Patrick Sawyer, who flew into Nigeria last month with the virus and infected 11 others before he died in July, including the male and female caregiver who both subsequently died of Ebola, Chukwu told reporters in Abuja, the capital.

Nigerian officials initially claimed the risk of exposure to others was minimal because Sawyer was whisked into isolation after arriving at the airport. But Lagos state health commissioner Jide Idris later acknowledged that Sawyer was not immediately quarantined the first day.

The latest two cases bring the total number of confirmed infections in Nigeria, including Sawyer, to 14. Five have died from the illness, five recovered and were discharged from hospital while another four are being treated in isolation in Lagos, the commercial capital where Sawyer's flight landed.

The development comes as African countries have tightened travel curbs in an effort to contain the Ebola outbreak. The restrictions ignore the World Health Organization’s (WHO) warnings that such measures could heighten shortages of food and basic supplies in affected areas.

Kalzeubet Payimi Deubet, Chad's prime minister, said on Thursday his country would close its border with Nigeria to prevent Ebola entering the country.

"This decision will have an economic impact on the region but it is imperative for public health needs," Deubet said.

While South Africa said on Thursday it was banning all travelers from Guinea, Liberia and Sierra Leone who not South African citizens from entering its territory.

WHO has repeatedly said that it does not recommend travel or trade restrictions for Liberia, Sierra Leone, Guinea and Nigeria — the countries affected by the epidemic that began in March.

Those countries are starting to suffer shortages of fuel, food and basic supplies due to these measures, it warned this week.

In the West Point slum in Liberia's capital Monrovia, the scene of violent clashes with the army on Wednesday after the area was quarantined to curb the spread of Ebola, hundreds of people jostled their way towards trucks loaded with water and rice.

Police used canes to beat back some locals while aid workers helped others dip their fingers in ink to record their ration.

More than 1,350 people have died from Ebola in the worst outbreak of the disease in history. Doctors Without Borders has said it could take months to bring the outbreak under control, even with sufficient international support for the countries affected.

Wire services