SoftBank Group Corp. Chief Executive Officer Masayoshi Son called the Japanese government "stupid" on Thursday for leaving regulations intact to prevent ride-sharing services from spreading in the domestic market.

"I can't believe there's such a stupid country," Son said during an annual company event in Tokyo. "I have a sense of crisis for this country, which is stopping its own (future) development."

Son said the mobility service could help reduce traffic congestion and accidents with vehicles equipped with artificial intelligence.

SoftBank is stepping up investment in ride-sharing companies such as Uber Technologies Inc., Didi Chuxing Technology Co. in China, Ola in India and Grab Taxi Holdings Pte Ltd. in Singapore. The company said in May it will invest $2.25 billion in General Motors Co.'s autonomous vehicle unit Cruise.

Ride-sharing services using private vehicles in Japan are only allowed in limited locations -- some rural areas in Hokkaido and in Kyoto Prefecture -- as the government is concerned about safety. Meanwhile, the U.S. and Chinese governments among others have relaxed laws to introduce such services.

While refraining from directly commenting on Son's remarks, Deputy Chief Cabinet Secretary Kotaro Nogami said at a press conference Thursday the government needs to look at various perspectives regarding ride-sharing such as how to secure safety and deal with liability issues when there are accidents.

Son also said at the event that SoftBank will speed up investment in companies providing services using AI technology as "those who control AI will control the future."

He said the use of AI will help cut costs and "redefine" various industries such as manufacturing, logistics, finance and health care.

"Japanese companies should make full and serious efforts on AI development," he said.

In a related move, Didi Chuxing said Thursday it has set up a joint venture with SoftBank and will start tests on taxi-hailing service in Osaka from this fall.

With more Chinese tourists visiting Japan, Didi will offer its AI-powered ride-hailing technology for free to taxi companies during the trial. It plans to gradually expand the service to other major tourist spots including in Tokyo, Kyoto, Fukuoka and Okinawa.

The technology predicts customer demand while collecting information on sales, operational rate as well as passengers' evaluations of the taxi drivers. Customers can call the taxis anywhere using a DiDi smartphone app.

Users of the Chinese-version of the DiDi smartphone app can pay through Alipay and WeChat Pay methods. DiDi said it has not decided how long the trials will last and that it will charge taxi companies for using the technology in the future.