A spokesman for China's Foreign Ministry has said the person suspected of wounding two Japanese nationals and a Chinese citizen in a knife attack at a Shanghai restaurant suffers from a mental disorder.

The wounded were taken to hospital in the aftermath of Tuesday's incident, while a suspect has been arrested by police with the case under further investigation, Guo Jiakun said on Wednesday.

Guo described Tuesday's incident as an isolated public security case which will be handled in accordance with the law. He also warned media outlets and individuals not to hype up the case and make irrelevant connections.