Sars is caused by a virus

Chinese state media said on Monday that 30 people had already volunteered to be the first subjects.

However, experts have warned that even if trials are successful, it will be a considerable time before a vaccine is made widely available.

Sars has killed 774 people and infected more than 8,000 worldwide since it emerged in southern China in 2002.

Zheng Xiaoyu, director of the state State Food and Drug Administration, told Chinese television: "There is still a lot of research work that needs to be done before this medicine can be effectively used."

China had said it planned to inject volunteers this month with a vaccine made from a dead sample of the coronavirus that scientists say causes Sars.

It said tests on animals have shown it to be effective.

Safety tests

The first phase of tests will be to find out if the vaccine is safe for humans, the official Xinhua News Agency reported.

The aim of the vaccine will be to provoke the body's immune system into action, so that it can destroy the Sars virus if infected.

Development of the Chinese vaccine is thought to have begun in April.

The World Health Organization has urged China to share the results of its tests with scientists in other countries.

Until a vaccine becomes available, the WHO says the best way to fight Sars is to identify cases at the earliest possible stage, and to ensure that they are isolated, and given treatment as quickly as possible.

Since December, China has reported three new cases of Sars - two patients who have recovered and another who is reportedly in stable condition in a hospital.