SHANGHAI — A knife attack at a restaurant in Shanghai injured two Japanese citizens and a Chinese national, prompting Japan's Foreign Ministry to demand a thorough investigation and issue a safety advisory for its nationals in China. The suspect, described by a spokesperson as a person with a mental disorder, was detained.

The victims were taken to a hospital for treatment, a spokesperson said. The two Japanese victims are men whose injuries are not life-threatening. One of them is a senior employee of a Japanese company with an office in the building where the attack occurred. The Chinese victim is a woman.

The Japanese government extended support for the injured men. Japan demanded a thorough investigation and a clear explanation by Chinese officials, severe punishment for the suspect, preventive measures and the protection of Japanese nationals in China.

Japan's Foreign Ministry issued a safety advisory urging Japanese citizens in China to be cautious and attentive, avoid going out alone and take care when accompanying children. Authorities are investigating the case, a spokesperson said. The spokesperson asked media outlets and others not to make groundless speculation about the case.

Ties between Beijing and Tokyo have been strained since Japanese Prime Minister Sanae Takaichi's comment in November that any Chinese military action against self-ruled Taiwan could be grounds for a Japanese military response. China subsequently imposed diplomatic and economic measures against Japan. The Chinese Embassy in Japan said in April it had received multiple threats and accused Japanese authorities of failing to take effective measures despite repeated reports to the police.