The ride-hailing giant Uber today conceded that the company is still using the "Greyball" software used to evade Portland regulators in 2014.

That admission is likely to add fuel to Portland City Hall's investigation of potential criminal or civil violations by Uber.

Last week, The New York Times revealed that when Uber operated illegally in 2014, it used a software called "Greyball" to evade a city crackdown. The app blocked suspected city inspectors, then filled the screens of inspectors' smartphones with fake rides while Uber drivers escaped undetected.

City officials launched an investigation this week, demanding to know if use of the software continued after the city entered into contracts with Uber in 2015. They also want to know who it was used to evade: inspectors or unwanted customers.

Today, Uber's chief security officer, Joe Sullivan, issued a statement saying Uber was banning its drivers from using "Greyball" any longer.

"We have started a review of the different ways this technology has been used to date," Sullivan said. "In addition, we are expressly prohibiting its use to target action by local regulators going forward. Given the way our systems are configured, it will take some time to ensure this prohibition is fully enforced."

The statement offers some direction to Portland transportation officials, but doesn't specify where or how drivers have used the software since 2014.

Here's Sullivan's full statement:

We wanted to give everyone an update on “greyballing”. This technology is used to hide the standard city app view for individual riders, enabling Uber to show that same rider a different version. It’s been used for many purposes, for example: the testing of new features by employees; marketing promotions; fraud prevention; to protect our partners from physical harm; and to deter riders using the app in violation of our terms of service.

We have started a review of the different ways this technology has been used to date. In addition, we are expressly prohibiting its use to target action by local regulators going forward. Given the way our systems are configured, it will take some time to ensure this prohibition is fully enforced. We’ve had a number of organizations reach out for information and we will be working to respond to their inquiries once we have finished our review.