A Chinese-developed vaccine against the H5N1 strain of bird flu in humans has been found safe in its first round of tests, a government news agency reported Monday.

Researchers began work on the vaccine last year and the government said it was ready to start mass production. But any vaccine would face more rounds of testing before it could be approved for human use.

Drug authorities said the vaccine "proved initially safe and effective" in its first round of tests, the official Xinhua News Agency reported. It didn't give any other details.

Chinese authorities say the vaccine is meant for high-risk groups such as poultry workers.

The U.S. National Institute of Allergy and Infectious Diseases is also conducting trials on an H5N1 vaccine for humans.

China has suffered 14 human deaths from the H5N1 strain of flu _ the latest a farmer who died July 12 _ and dozens of outbreaks among its vast poultry flocks.

Experts fear the virus could mutate into a new strain that could spread easily from human to human, potentially causing a global pandemic.