Japan's ambassador to Beijing has asked for more security for Japanese nationals in China after a 10-year-old Japanese boy was killed this week in a knife attack that was the second to target school students.

The killing of a Japanese schoolboy in the Chinese city of Shenzhen has sparked worry among Japanese expats living in China, with top firms warning their workers to be vigilant. Toshiba and Toyota have told their staff to take precautions against any possible violence,