China may have had more H1N1 flu deaths than have been reported, with some local governments possibly concealing suspect cases, a prominent Chinese medical expert said in an interview published on Thursday.

Zhong Nanshan, a doctor based in the far southern province of Guangdong, said he doubted the current official death toll from the influenza strain, also called "swine flu", that has medical experts worldwide worried.

"I just don't believe that nationwide there have been in all 53 H1N1 deaths," Zhong told the Southern Metropolis Daily, a popular Guangdong newspaper.

Zhong said that "some areas have not been testing deaths from severe (pneumonia) and treating them as cases of ordinary pneumonia without a question," the paper reported.

Zhong is respected by many people in China for his candour and work in fighting "severe acute respiratory syndrome" (SARS) in 2003, when nationwide panic and international alarm erupted after it emerged that officials hid or underplayed the spreading epidemic.

China, the world's most populous country, has reported 28 new H1N1 deaths in the last week during a cold snap across much of the country, the Ministry of Health said on its website (www.moh.gov.cn).

The latest national death tally issued on Monday on the same website showed 53 death cases.

The H1N1 flu strain affects the respiratory tract and patients who become severely ill or die typically suffer from pneumonia which is brought on either directly by the virus or due to secondary bacterial infections owing to the person's weakened immune system.

"It's irresponsible to treat these cases as ordinary pneumonia deaths," Zhong said of untested deaths, according to the paper.

Zhong said his home Guangdong province was acting responsibly, but the report did not say which areas he had doubts about.

Cover-ups by local governments in 2003 during the SARS epidemic led to the sackings of several officials. More than 300 people died in that outbreak.

The Health Ministry did not have immediate comments on Zhong's remarks.

Zhong said China's peak flu season will start in December and last until February next year in the north of the country, a time when Chinese gather for the traditional Lunar New Year.

China is preparing for possible wider outbreaks. More than 34.8 million people have received free vaccination until Wednesday, the ministry said.