An Indonesian man has died of bird flu, the health ministry said Saturday, in the country's ninth fatal case this year.

"The deceased was a self-employed 37-year-old male," according to the report on the ministry's website.

The man was hospitalised on July 24 with a high fever and was placed on a ventilator five days later, according to the report. He died on July 30.

Authorities do not know how the man contracted the virus, but said he lived near .

Indonesia has been hardest-hit by bird flu, with 159 fatalities reported since 2003 out of 359 worldwide, according to figures, which include the latest death.

Bird flu, also known as the , typically spreads from birds to humans through direct contact, but experts fear it could mutate into a form that is easily transmissible between humans.