A Liberian man carrying the Ebola virus flew into the Nigerian city of Lagos and immediately collapsed on his arrival at the airport and died five days later.

Patrick Sawyer, 40, reached Lagos, Africa's most populous metropolis, on Sunday, 20 July. Following complaints of fever, vomiting and diarrhoea, he was immediately taken to hospital where his condition kept deteriorating.

"The patient was subjected to thorough medical evaluation where laboratory investigations were carried out. His blood sample was taken to the advanced laboratory at the Lagos University Teaching Hospital, which confirmed the diagnosis of Ebola Virus Disease.

"The result was corroborated by other laboratories outside Nigeria. Despite the urgent specialised barrier nursing care provided for the patient in Lagos, the patient unfortunately passed away in the early hours of July 25, 2014," Nigerian health minister Onyebuchi Chukwu told reporters.

Shortly after Sawyer was diagnosed with the Ebola virus, the passenger manifest of Asky Airline, which flew the stricken man, was pulled out by the health officials to check whether any of the other travellers were at risk.

The virus is not airborne and experts say there is little chance that Sawyer could have infected anyone. The disease spreads from one person to another through blood or other bodily fluids.

Sawyer, who was an employee of a West African organisation in Monrovia, was kept in isolation as soon as the medical tests confirmed the presence of the pathogen and he did not enter the city.

Nonetheless, the Nigerian health ministry asked the public to be on alert over the situation in the backdrop of the sudden Ebola outbreak in western African countries in recent weeks.

"All government tertiary health institutions in Nigeria have been equipped to handle any emergency that may arise from the disease," said the Nigerian health minister.

Ebola is an extremely deadly virus with a killing ratio of about 90%. Causing diarrhoea and internal bleeding, the virus weakens the functions of the kidney and the liver.