BEIJING -- China's national air carrier and health officials concealed information that might have saved lives and stopped a chain of SARS infection across East Asia, according to interviews and a review of the government's actions after a flight on which two dozen people were thought to have been infected.

Last Sunday, the Globe reported on 21 cases of people who had contracted severe acute respiratory syndrome, including three passengers who died, after flying March 15 on Air China Flight 112 from Hong Kong to Beijing. A 72-year-old man with SARS was on the flight. He is said to have spread the virus to other passengers. It then spread to Hong Kong, Taiwan, Singapore, Beijing, Inner Mongolia, and beyond.

The World Health Organization, which had said that nine people were infected on the flight, revised its statistics on Friday to reflect the new information. Some victims sat five to seven rows from the sick man, well beyond the accepted ''close contact'' risk area for SARS, said Dr. Max Hardiman, WHO's chief for international health regulations.

Two months ago, Flight 112's poisonous trail was apparent, but Chinese officials hid the news and delayed informing victims. China's Centers for Disease Control said that a ''full investigation'' was launched, tracing all passengers in China three days after they had learned that a man on the flight had SARS. The 72-year-old Beijing man was hospitalized on March 16 and died four days later.

On March 24 and 25, two flight attendants on Flight 112 checked into an Inner Mongolia hospital with high fever, unaware they had contracted SARS. On March 25, Hong Kong authorities alerted Air China and media that at least nine Hong Kong passengers had SARS. No warning was published or broadcast by Air China or Chinese media, and the flight attendants said Air China never alerted them.

Two days ago, an Air China official insisted he had no confirmation that numerous people had been infected on the flight.

If passengers were contacted, it was not soon enough to stop two Chinese trade officials who contracted SARS on Flight 112 from flying to Bangkok, where one fell sick and visited a local clinic. Shaking with fever, Zhu Hong flew back to Beijing on March 23, fatally infecting a Finnish man who sat next to him.

Eleven days after Zhu -- a senior Commerce Ministry official -- was hospitalized in the SARS ward of Beijing's Ditan Hospital on March 26, health officials announced the death of Pekka Aro, the 52-year-old Finn, at the same hospital, but said his illness could not be linked to anyone in China.

''He probably contracted it abroad, but fell ill after arriving in Beijing,'' Guo Jiyang, deputy director of the Beijing Health Bureau, said at a news conference on April 6.

A Beijing public health official, who requested anonymity, said that in the last week of March, authorities traced people aboard the March 23 Thai Air flight on which Zhu sat next to Aro, indicating that Guo and other health officials should have known how Aro contracted the disease -- and could have warned him. Believing he had the flu, Aro delayed seeking treatment and died.

A month later, after a Chinese military doctor told foreign media that SARS cases were being hidden, China's Health Ministry announced on April 20 that all cases would be revealed. China's leaders threatened punishment for any coverup. The health minister and Beijing's mayor were fired, but Guo and others have retained their jobs.

The Beijing health official said most of the Chinese and foreign residents of China who were on Flight 112 and the Thai Air flight were contacted in late March. The two Air China flight attendants who fell ill -- two of the easiest people to trace -- said no one warned that they had been exposed to a deadly disease, information that could have protected them from fatally infecting others.

An Air China official, who identified himself only as Wang, insisted on Friday that ''crew only refers to pilots,'' justifying the airline's claim on its website that no crew members have caught SARS. He said he knew about Flight 112, ''but we do not know the exact number of people infected. . . . WHO has never told us.''

Wang said passengers are now eligible for free SARS insurance to cover $24 per day in hospital bills, up to a maximum of $2,427, if they are infected on an Air China flight. Their relatives will be paid $24,184 if they die, he said.

One of the flight attendants -- who infected her husband, who died, as well as her parents and brother -- said on Friday from Inner Mongolia that Air China has not paid her medical bills, which have topped $30,000.

Meng Chunying, 27, was hospitalized on March 25, the same day the Hong Kong Health Department informed Air China's Hong Kong office and the Hong Kong public that at least nine tour group members on Flight 112 had SARS. Ultimately, 10 members of the group fell ill, two of whom died.

On April 1, an Air China doctor told Meng ''the good news,'' that ''the SARS patient did not fly on our airline,''' she said. She said that she only learned there was a SARS patient on her flight from a New York Times reporter. Meng later heard Air China's chief executive held a meeting on March 26 ordering the disinfection of the affected Boeing 737 and alerting ''relevant hospitals.'' Meng and her colleague Fan Jinling, 28, said no alert came to their doctors.

Among the people Meng infected were her doctor and a fellow patient, who fatally infected his wife, and his three children, an outbreak that Inner Mongolia health officials said was the origin of most of the region's 300 cases.

Meng was told her health insurance does not cover SARS. Air China, a state-owned company, loaned her $4,600, less than one-sixth of what her family had borrowed to treat five people, she said. She is considering suing but would prefer to settle the case amicably. Air China officials ''now tell me they will try their best to solve the difficulties I have,'' she said.

This story ran on page A3 of the Boston Globe on 5/25/2003.