The US Federal Trade Commission said Monday that it has sued Uber Technologies (UBER) for allegedly running "deceptive" billing and cancellation practices pertaining to its Uber One subscription service.

The service costs $9.99 per month and offers discounts on fees related to the company's ride-hailing and food-delivery apps.

In its lawsuit, the antitrust regulator alleged that Uber enrolled consumers in the subscription service and charged them without consent, while failing to deliver on the promised savings.

"We're alleging that Uber not only deceived consumers about their subscriptions, but also made it unreasonably difficult for customers to cancel," FTC Chairman Andrew Ferguson said in a statement.

Uber "wrongly" promises monthly savings of $25, and charges users before their billing date following the sign-up process, the FTC alleged.

Uber's shares were down 4% in Monday late-afternoon trade amid risk-off mood in broader equity markets.

The company denied the allegations and said it was "disappointed" with the FTC's move.

"Uber One's sign-up and cancellation processes are clear, simple, and follow the letter and spirit of the law," an Uber spokesperson said in a statement e-mailed to MT Newswires. "Uber does not sign up or charge consumers without their consent, and cancellations can now be done anytime in-app and take most people 20 seconds or less."

Last month, Uber terminated its proposed $950 million deal to acquire Delivery Hero's Foodpanda business in Taiwan amid regulatory hurdles.