A knife attack at a supermarket in Shanghai has killed three people and injured 15 others.

The city's public security authorities say a man slashed at many people at the suburban supermarket on Monday evening. They say victims were taken to hospital, but three of them died.

The authorities detained a 37-year-old male suspect on the spot.

They say their initial investigation found that the man had a personal financial dispute and came to Shanghai to vent his anger.

The Japanese embassy is calling for caution, citing a recent series of knifing incidents in China.

Officials are urging Japanese nationals to be on the alert for suspicious people approaching them and take safety measures, such as avoiding going out alone.

In September, a 10-year-old Japanese boy was fatally stabbed on his way to a Japanese school in the southern city of Shenzhen.