China, where deadly SARS first emerged in 2002, is on the alert for fever among groups of flu sufferers in its freezing capital, Xinhua news agency said on Tuesday.

Severe Acute Respiratory Syndrome, the symptoms of which are similar to those of flu, spread as far afield as Canada before it was brought under control in 2003. It killed close to 800 people out of the 8,000 known to have been infected.

"Beijing municipal health authorities have called for close monitoring of people suffering respiratory infectious diseases as the city has been beset by flu and colds since the New Year," Xinhua said without reference to SARS which, at its height, put Chinese airports on alert, monitoring the temperature of incoming tourists.

"The Municipal Health Bureau ordered medical workers at disease control centres to remain on high alert and report the first occurrence of fever involving a group of people and handle such cases as quickly as possible."

The bureau had also urged hospitals to put more doctors and nurses on duty and take measures to prevent cross-infection between patients.

Cold and flu sufferers in Beijing had hit record highs in many hospitals this winter, Xinhua said on Monday, putting part of the blame on smog.