AFP (Beijing) - A commentary in China's leading state-run newspaper on Wednesday called for improved road safety in the world's biggest car market after two fatal school bus crashes sparked a public outcry.

On Monday 15 primary school children died when the bus  were travelling in rolled into a river, following the deaths of 19 children last month in an overcrowded, nine-seater bus.

The latest accident has provoked an outpouring of anger on China's hugely popular weibos, microblogs similar to Twitter, over the safety of school buses.

"Another school bus accident kills 15 children. It's just a number in the eyes of Chinese officials," wrote "luoming0726" on the Tencent weibo. "The only thing they care about is whether it impacts their future career."

The commentary in the People's Daily said China, once the kingdom of the bicycle and now the world's largest car market with 1.34 million passenger vehicles sold in November, had not yet developed a mature driving culture in which road rules were obeyed.

"Vehicle standards have improved, but we are still weak on safety, and if we don't raise the capacity for drivers to control their cars, we will still be heading for disaster," wrote Zhan Yong.

"School buses should improve their own standards, but when other vehicles ignore traffic rules, we may be flying into unexpected calamity," Zhan wrote.

Chinese school buses are often crammed, especially in rural areas, due to lax rule enforcement, in a country where, according to police statistics, almost 70,000 people died in road accidents in 2010 -- around 190 a day.