European airports from London to Moscow stepped up checks Wednesday on flights from the Chinese city at the heart of a new SARS-like virus that has killed 17 people and spread to the United States. The coronavirus has sparked alarm because of its similarity to the outbreak of SARS (Severe Acute Respiratory Syndrome) that killed nearly 650 people across mainland China and Hong Kong in 2002-03.

The new virus emerged on the eve of the Lunar New Year holiday during which hundreds of million travel across China to meet up with their families.

"The upcoming Chinese New Year celebrations at the end of January will cause an increased travel volume to/from China and within China, hence increasing the likelihood of arrival in the EU of possible cases," the European Centre for Disease and Prevention and Control (ECDC) said in a statement.

"There is considerable uncertainty about the mortality and morbidity of this disease, and more epidemiological data is urgently needed to get a better understanding of this virus."

It put the likelihood of the virus spreading to Europe as "moderate".

Health authorities in Britain introduced "enhanced monitoring" for the three weekly flights from Wuhan - the central China city from where the virus spread - to London's Heathrow.

Public Health England also raised the risk level of an infection from "very low" to "low" because of the potential for human-to-human transmission.

The measures could be expanded to "other Chinese departure points if necessary", it said.

The United States on Tuesday confirmed its first case of a person with the new virus. European countries have registered no cases to date.

Italy's health ministry said it would introduce temperature checks for passengers arriving on the next scheduled direct arrival from Wuhan to Rome's Fiumicino airport.

The airport has three direct flights a week with Wuhan.

Russia's health and sanitation watchdog strengthened checks at airports and other border crossings from its giant southern neighbour.

Masked health officials boarded some flights from China to check passengers' temperature with hand-held heat sensors. "All flights from China arriving at (Moscow's) Vnukovo airport undergo additional sanitation and quarantine controls," Russia's health and sanitation agency spokesman Andrei Polyuakov told reporters.

Romanian health authorities said their measures would start on Thursday. French Health Minister Agnes Buzyn said authorities were monitoring the situation but not following countries such as Russia, which has put up posters telling passengers what to do in case of symptoms.

Such measures are not recommended by the World Health Organization (WHO), Buzyn said, and are "not very effective".

A WHO spokesman said Tuesday that "based on currently available information, there is no justification for any restriction of travel or trade".

Health authorities in Germany and countries Scandinavia said they had also refrained from taking any measures at airports.