The dead woman, surnamed Wei, was the mother of a researcher who became the first person to be confirmed as a Severe Acute Respiratory Syndrome (SARS) patient in this latest outbreak.

She was previously listed as a suspect case and died on April 19 in eastern Anhui province.

Her death is the first attributed to the respiratory disease in China since July 27 last year, when a deadly outbreak claimed the lives of 349 people here. Almost 800 people died worldwide.

The confirmation that Wei had SARS brought to five the number of confirmed cases in Beijing and Anhui. One was listed in critical condition. There were also four suspected cases, all in Beijing.

All the cases can be traced back to the Institute of Virology in Beijing where the researcher worked, health officials have said. It has since been shut down while investigations are carried out.

Although the outbreak appeared to be isolated to the laboratory, central authorities were taking no chances, issuing an urgent notice ordering all local governments to step up prevention work to stop the disease spreading.

"All places and all departments should pay high importance to SARS prevention and control work," the State Council said on the eve of holidays, which see a large chunk of China's 1.3 billion people crowd onto public transport.

The order, reported in the People's Daily, also demanded authorities "do not cover-up, delay or deny SARS reports".

China initially covered up SARS last year. The disease spread to some 30 countries.