(Reuters) – A sweeping investigation by the city of Portland, Oregon, found that Uber Technologies Inc [UBER.UL] used a software tool to intentionally evade 16 government officials whose job it was to regulate the ride-services firm, city officials said on Thursday. It did not have any licenses, so it used a software tool it had created called from booking rides Greyball to block regulators when Uber started operating in December 2014. Uber stopped using the software after it received approval to operate its service in Portland in April 2015. The city imposed no penalties or other penalties but transportation officials have recommended that the city ramp up enforcement efforts. “We’ve ensured that no efforts to evade regulators or deny service to riders” will be allowed in the future, Portland City Commissioner Dan Saltzman said in a statement. Portland launched its investigation after the New York Times reported in March that Uber used Greyball to evade government officials in areas where its service hadn’t yet been accepted, such as Portland, Boston, Paris and Las Vegas, and in countries such as Australia, China, Italy and South Korea. Greyball allowed Uber cancel or to ignore ride requests from accounts and from places near enforcement agencies. The tool also allowed Uber to demonstrate that no cars were available. FILE PHOTO: An Uber sign points to drop off and pick up place on a city street in Portland, Oregon March 19, 2016. REUTERS/Mike Blake Portland found that when Uber started working in town in December 2014, the business used 17 rider accounts, 16 of which belonged to police officers to be blocked by Greyball, and deny 29 ride requests by city transportation enforcement officers. “In using Greyball, Uber has sullied its own reputation,” the Portland Bureau of Transportation wrote in its report. A spokesman for Uber said the company was “pleased the investigation was shut” and “will continue working in partnership with the City of Portland.” Following the Times story, Uber said it would put a stop to using the technology and acknowledged Greyball’s presence. The U.S. Department of Justice also opened a criminal investigation into Greyball, sources said in May. Greyball is just one of a string of scandals this year, Uber has weathered, such as a lawsuit threatening its car business and allegations of sexual harassment. Uber’s main U.S. rival, Lyft, also cooperated with the Portland investigation, but regulators found no evidence Lyft had engaged in similar tactics. Reporting by Heather Somerville at San Francisco; Editing by Edwina GibbsOur Standards and Lisa Shumaker:The Thomson Reuters Trust Principles.