The World Health Organisation reported that a Qatari man is suffering from a new respiratory virus from the same family as the deadly SARS.
"He is still in critical condition" at a London hospital, Gregory Haertl, a spokesman for the United Nations health body, told reporters in Geneva.
The 49-year-old Qatari was admitted to an intensive care unit in Doha on September 7 suffering from acute respiratory infection and kidney failure before being transferred to Britain by air ambulance on September 11, the WHO said.
A Saudi Arabian national died earlier this year from a virtually identical virus, the WHO said.
The WHO confirmed the illness was in the coronavirus family but was not SARS, or Severe Acute Respiratory Syndrome, which swept out of China in 2003, killing more than 800 people worldwide.
Haertl stressed Tuesday that the coronavirus family also includes other viruses, including the common cold, and insisted the new virus was not SARS.
"This is not SARS, it will not become SARS, and it is not SARS-like," he said, pointing out that what sets the new virus apart was that it caused rapid kidney failure.
The WHO is cooperating with national health authorities in a bid to detect other cases, and was planning to publish an update later Tuesday, Haertl said.
He stressed though that very little was known about the new virus so far, pointing out that there were only two confirmed cases, which popped up three months apart and with no connection besides the fact that both men had links to Saudi Arabia.
"We don't know yet how it transmits... if it's human to human or animal to human," he said, pointing out that the virus might also provoke milder, and therefore undetected illness.
"We are very much in an investigative period," he said.