The southern Chinese city government said in a statement late Sunday that the man, 32, had "tested negative for Ebola virus upon preliminary laboratory testing".

"In the past one month... he had no contact history with sick persons or animals and did not visit health-care facilities. He is currently in stable condition," a government spokesman said in the statement.

The man arrived in Hong Kong from Lagos, Nigeria's most populous city, via Dubai on Thursday and was hospitalized Sunday after vomiting and having diarrhoea.

Concerns are growing over the potential spread of the disease which has claimed nearly 1,000 lives in west Africa this year.

Hong Kong, a densely populated city of some seven million people, is particularly alert to the spread of viruses after Severe Acute Respiratory Syndrome killed almost 300 people eleven years ago.

On July 30 the Hong Kong government said it would quarantine as a precaution all people from Ebola infected areas who showed any symptom of the disease such as fever, vomiting or diarrhoea.

Last week a woman who showed Ebola-like symptoms after returning from a holiday in Kenya tested negative for the virus.

Nigeria along with Guinea, Sierra Leone and Liberia have been hardest hit by the latest epidemic, which the WHO has called the worst outbreak of its kind in four decades.

Nigeria -- the most populous nation in Africa -- confirmed two new cases Friday of the often fatal hemorrhagic disease, bringing the total number of infections to nine, including two deaths.

The World Health Organization has declared the epidemic an international health emergency, as countries scramble to impose measures to prevent any spread of a contagion that has claimed almost 1,000 lives.