TOKYO -- Uber Technologies' attempt to launch a ride-sharing service in Japan has run up against a regulatory wall here, as it has in many other countries.

Japanese transport services regulators have ordered the U.S. company to stop the experimental free ride service it started in the city of Fukuoka in February.

The trial service was intended as the first step in rolling out a full-fledged taxi-like service that matches passengers with private drivers by using a smartphone application.

But the transport ministry has barred Uber from continuing the pilot project, saying it is effectively an illegal unlicensed taxi operation.

Uber's ride-sharing service has been stirring up regulatory controversies around the world.

On Feb. 5, Masami Takahashi, head of Uber's Japanese unit, received a message sent to his smartphone, saying, "Please contact me immediately." It was from the official in charge at the transport ministry.

Takahashi, who was in Fukuoka to monitor the launch of the program, had to return to Tokyo quickly.

A ride-sharing service connects individual private drivers with people who ask for a ride through a smartphone application. Users pay the drivers for their services.

Uber operates the service in about 150 cities worldwide.

The company has been aware that its business model cannot work in Japan, where unlicensed taxi operations are banned by the road transportation act.

The company tried to sidestep the rule by launching the pilot project in Fukuoka, claiming its purpose was to collect data for research in urban transportation needs. The firm cast the project as a joint experiment with Kyushu TLO, a business affiliated with Kyushu University.

Under the program, users were not required to pay fees to the drivers, who received payments from Uber for helping it collect data.

Neither Uber nor the transport ministry, however, made serious efforts to figure out a way to formulate the new service as a legitimate business.

Uber didn't try to gain the ministry's permission for the project, which it claimed was carried out under the framework of the existing law.

The firm explained the project to the ministry only two days before it was started.

The official in charge at the ministry says the brief oral explanation given by the company was not enough to judge whether it was legal or not.

The transport ministry had to start studying details of the service on its own after it was launched.

The ministry found that the contract between the company and the drivers involved was identical to that used by Uber's Dutch unit, which had previously started a similar service.

The regulators also discovered significant differences between their notions about fees for information and insurance and those of Uber.

Uber didn't see the transport ministry as the regulatory organization in charge of supervising its experiment, while the ministry showed no interest in permitting the new service.

Eventually, the ministry decided that the fees Uber paid to the drivers for data they collected for the company were inseparable from the transportation service, and that made the project a violation of the road transportation act, according to Hidetaka Sakai, an official at the ministry's passenger transport division at the road transport bureau.

Uber was forced to terminate the experiment on March 4, just one month after it began.

Founded in 2009, Uber uses a smartphone application to dispatch taxis and hired cars to passengers through crowdsourcing.

The company operates this service in 290 cities in 55 countries and regions around the world.

It began operating in Japan in 2013 with a taxi-hailing service, and dispatched a total of 140 million taxis in 2014.

The company launched its first ride-sharing service in 2013 in the U.S. The service has been gradually gaining population in various parts of the world while causing the kind of friction with local regulators that it has created in Japan.

One observer said the company has managed to keep growing by recruiting politically influential people such as a former campaign manager for U.S. President Barack Obama and senior members of the New York City Taxi and Limousine Commission, and by spending lavishly on lobbying.

But Uber co-founder and CEO Travis Kalanick rejects this argument, claiming the company's business has grown because it has expanded transportation options for consumers, created new jobs and contributed to reducing drunk driving.

Many investors are apparently betting on further expansion of the company's global operations. Its capital increase in 2014 boosted the firm's value to $41 billion.

Uber's ride-sharing service is one of the most successful business models based on the principles of the "sharing economy," which also includes house sharing and car sharing.

"To create a sustainable society, it is important for people to embrace car sharing as opposed to individual car ownership," said Uber's Takahashi. The company has already started considering a second phase of its experiment in Japan.

It will take society awhile to determine whether ride sharing should be rejected as a violation of the law or embraced as a beneficial innovation.