A man in southwest China who contracted the bird flu virus died on Sunday, health authorities said, the second human death from the virulent disease in the country in just under a month.

The news comes after neighbouring Vietnam, Cambodia and Indonesia also reported deaths from avian influenza, and after chickens tested positive for the H5N1 virus in Hong Kong, prompting a mass cull of birds.

The latest Chinese victim fell ill on January 6 and was admitted to hospital in Guiyang -- capital of Guizhou province -- where his condition rapidly deteriorated, the provincial health department said in a statement.

Tests on the patient before he died confirmed he had contracted the H5N1 virus, it added.

"So far, 71 people who had close contact with the victim have not developed abnormal symptoms," the health department said.

He is the second man to die from bird flu in China in less than a month, after a bus driver in the southern province of Guangdong passed away from the disease on December 31.

The latest death brings to 28 the number of people in China who have died from the disease -- which is fatal in humans in about 60 percent of cases -- since 2003, out of 42 reported human cases.

The Hong Kong Department of Health said in a statement Sunday it had been notified of the case by the mainland's health authorities, which said the patient was 39 years old.

Authorities from Hong Kong and the mainland have been working closely together since three chickens in the Chinese territory tested positive for the H5N1 virus in mid December.

Most human infections are the result of direct contact with infected birds, and the virus does not pass easily among humans.

The World Health Organization (WHO) says it has never identified a "sustained human-to-human spread" of the virus since it re-emerged in 2003.

But according to the Hong Kong health department, the Guizhou province victim, who has not been named, had not reported any obvious exposure to poultry before the onset of symptoms.

The Guangdong victim, whose surname was Chen, had not had any direct contact with poultry either in the month before he was taken ill, nor had he left the bustling southern metropolis of Shenzhen where he lived.

Aside from China, Vietnam on Thursday reported its first human death from the virus in nearly two years, and the disease also claimed the life of a toddler in Cambodia.

Indonesia, meanwhile, on Friday reported its second human death from bird flu this year when a five-year-old girl who recently lost her relative to the deadly virus also passed away.

China is considered one of the nations most at risk of bird flu epidemics because it has the world's biggest poultry population and many chickens in rural areas are kept close to humans.

But the Guizhou health department sought to ease concerns on Sunday, saying bird flu was "preventable, controllable and treatable."

All in all, the avian influenza virus has killed more than 330 people around the world, and scientists fear it could mutate into a form readily transmissible between humans, with the potential to cause millions of deaths.

Highlighting those fears, the WHO said last month it was "deeply concerned" about research into whether H5N1 could be made more transmissible between humans after mutant strains were produced in labs.

Two separate research teams -- one in the Netherlands and the other in the United States -- separately found ways to alter the virus so it could pass easily between mammals.