Sierra Leone's top Ebola doctor has died from the disease, medical officials have said.

Sheik Umar Khan was infected earlier this month and died on Tuesday at a ward run by medical charity Doctors Without Borders in the far north of the country.

Miatta Kargbo, Sierra Leone's health minister, called Khan a "national hero" and praised his "tremendous sacrifice" in working to save the lives of others.

His death comes days after Samuel Brisbane, a senior doctor at Liberia's largest hospital, died on Saturday at an Ebola treatment centre on the outskirts of Monrovia.

Several other medics have also been infected. The aid group Samaritan's Purse said on Saturday that a US doctor, Kent Brantly, who was working in Liberia was also sick.

Health workers are at serious risk of contracting the disease, which spreads through contact with bodily fluids.

Azaria Marthyman, a Canadian doctor, has put himself in quarantine as a precaution after spending weeks in Liberia treating patients with the deadly Ebola virus alongside an American doctor who is now infected, local media said on Tuesday.

Meanwhile, Pan-African airline ASKY suspended all flights to and from the capitals of Liberia and Sierra Leone over the worsening Ebola health crisis.

Ebola has killed hundreds of people in West Africa in the worst outbreak on record. The World Health Organisation says that 219 people in Liberia, 319 people in Guinea, and 224 in Sierra Leone have died.

Nigeria death

The disease has also killed the Liberian husband of an American woman who had flown to Lagos, Nigeria.

The family of Patrick Sawyer, a 40-year-old who died on July 24, said he had recently arrived from the US for a visit. Health officials said his family members were not affected.

Officials stressed people were not contagious until they showed symptoms, and the Sawyer family left Liberia days before he fell ill.

Sawyer, a consultant for Liberia's Finance Ministry, collapsed on arrival at Lagos airport. He was put in isolation at the First Consultants Hospital in Obalende.