World Health Organisation experts say a new respiratory illness from the same family as the SARS virus appears not to spread easily.
A 49-year-old Qatari man is being treated for the virus in Britain.
The first person known to have had the disease, in Saudi Arabia, died.
The WHO says it appears the new virus cannot be easily transmitted from person to person.
Hundreds of people died from the Sars virus, which emerged in China in 2002.