An immigration officer wears a face mask at the Nnamdi Azikiwe International Airport in Abuja, Nigeria Reuters

Every citizen of the world is at risk of contracting Ebola, the Nigerian government has warned.

Health Minister Onyebuchi Chukwu made the comment during a briefing with journalists in which he said that as long as people travel from one country to another, every place in the world is at risk.

Chukwu also said that Nigeria has not defeated the virus yet.

"While Nigeria has successfully contained Ebola, it hasn't eliminated the disease. As we speak, there is a case we are still managing. And even that case we are still managing must also have had her own third-degree contacts, many of whom are part of this number of people that are under surveillance.

"So, until we give a clean bill of health to every contact, we cannot even say we have eliminated the disease. We will only stop being at risk when the very last case of Ebola virus disease under this current epidemic has gone," he continued.

"It is still possible that Nigeria may record between one to three new cases because there are people under surveillance. We should not move from panic to euphoria."

Chukwu's comments came as a Nigerian doctor died from the virus in the oil hub city of Port Harcourt. His wife is still in quarantine.

The doctor became infected by a man linked to the first case in Nigeria, Patrick Sawyer, who brought the virus to Lagos.

On Thursday, the World Health Organisation (WHO) warned the virus could have hit at least 20,000 people.

"The outbreak continues to accelerate," WHO said.

At least 1,552 people have died since the outbreak- the worst in history – started last March.