Health officials have said a deadly virus which has killed 18 people worldwide appears to be able to spread from person-to-person.
There have been 34 reported cases of the Sars-like novel coronavirus, known as hCoV-EMC, which causes severe pneumonia in victims and sometimes kidney failure.
It is most closely related to a bat virus and scientists are considering whether bats, camels or goats are a possible source of infection.
The virus was first detected in mid-2012, with most of those infected identified as having travelled to Qatar, Saudi Arabia, Jordan or Pakistan.
The UK has had four cases, two of whom died.
It comes after France confirmed a second case of the virus on Sunday, with a hospital roommate of a 65-year-old man who initially contracted the virus testing positive for the illness.
The second patient's condition has deteriorated and requires treatment in intensive care at a hospital near Lille, Health Minister Marisol Touraine said.
The outbreak of Severe Acute Respiratory Syndrome (Sars) killed 775 people after originating in Asia in 2003.
Keiji Fukuda, Assistant Director-General at the World Heath Organisation (WHO), said it appeared likely the virus could be passed through close contact between people.
But he said there was no evidence it was able to sustain "generalised transmission in communities" - a scenario that would raise the spectre of a pandemic.
A statement from the WHO added: "Of most concern, however, is the fact that the different clusters seen in multiple countries increasingly support the hypothesis that when there is close contact this novel coronavirus can transmit from person-to-person."
The latest confirmed cases of the virus are in Jordan, Qatar, Saudi Arabia, the UAE, UK and France.