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 Asian country in just under a month.

Concerns about avian influenza have risen across southeast Asia after China in late December reported its first fatality from the H5N1 virus in 18 months.

The latest victim fell ill on January 6 and was subsequently 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 bird flu 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.

The discovery prompted Hong Kong authorities to cull thousands of chickens in a bid to contain the spread of the virus among poultry.

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 says it has never identified a "sustained human-to-human spread" of the virus since it re-emerged in 2003.

But according to health authorities, the man who died in Guizhou had not reported any obvious exposure to poultry before the onset of symptoms.

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

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

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

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.

In total, 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 World Health Organization 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 H5N1 so it could pass easily between mammals.