After contracting an infection similar to the deadly SARS virus, a Qatari man is critically ill in a London hospital reported World Health Organisation.
"The Qatari man was at a hospital in Qatar and medevacked to Britain where he was taken to an intensive care unit at a specialised hospital," said WHO spokesman Gregory Hartl.
The 49-year-old patient, whose name was not given, was suffering from acute respiratory infection and kidney failure, the WHO said.
Another person had died from a similar virus in Saudi Arabia in recent months, Hartl told AFP, adding though that for the moment it was impossible to link the two cases.
"We haven't heard of any more new cases. We don't have an appreciation of how widespread the virus is," he said.
"This is one reason why we're trying to get more information. We don't know how it's transmitted," he added.
The new illness is caused by a coronavirus, the same family as the SARS virus that emerged in 2002 and eventually killed 800 people.
SARS was recognised at the end of February 2003.