The herder was killed while blocking the road through his village during a protest against noise and pollution from coal trucks

China has executed a truck driver for killing an ethnic Mongolian herder in a case that sparked Inner Mongolia's largest demonstrations in 20 years.

The official Xinhua news agency said in a brief report that Li Lindong had been executed on 18 August. The report, dated 19 August, was posted to a regional news website and appeared not to have been widely circulated.

The herder, Mergen, who like many Mongols used just one name, was killed on 10 May while he and others were blocking the road through their village to protest against noise and pollution produced by coal trucks driving across the grasslands. Police said Li ran over Mergen and then dragged his body for 145 metres before he died.

His death and that of another Mongol in a clash with Chinese coalminers sparked protests across the sprawling northern pastureland by herders and students demanding justice and greater protection for Mongol culture and the nomadic herding lifestyle.

Li was sentenced in June after a six-hour trial at the intermediate people's court in the region's Xilingol League area. Fellow driver Lu Xiangdong, who had been sitting in the cab of Li's truck when he drove over the herder, was also convicted of homicide and sentenced to life in prison, state media said earlier.

Two other people, Wu Xiaowei and Li Minggang, were convicted of obstructing justice and given three-year sentences for blocking police who arrived at the scene, allowing Li Lindong and Lu to escape.

Mass migration to the Inner Mongolia region by members of China's majority Han ethnic group and a booming mining industry have placed traditional ways of life under severe pressure.

China is the world's largest enforcer of the death penalty and is believed to execute more people each year than the rest of the world combined, although the actual figure is a state secret.