UPDATE: This article has been updated with a comment from Uber provided to IBTimes UK regarding its updated privacy policy.

Uber is facing criticism from privacy advocates and a legal challenge in the US over a new policy that will allow the company to track users even when the Uber app is not in use.

The new policy, set to be introduced on 15 July, will mean that Uber is able to keep track of users' location data when the app is closed and the smartphone's GPS is disabled.

Speaking to IBTimes UK, Jim Killock, from non-profit organisation Open Rights Group, said that the updated privacy policy is a violation of Uber customers' digital rights.

"There is no need for Uber to know where their customers are when they are not trying to get a taxi," Killock said. "Collecting this information is both greedy and creepy."

The changes will also allow the firm to access its customers' contact details in order to send "special offers to riders' friends or family".

In response to the planned update, US-based civil liberties group Electronic Privacy Information Center (Epic) submitted a complaint to the Federal Trade Commission (FTC) requesting an investigation into Uber's business practices.

The complaint reads: "[The policy change will] threaten the privacy rights and personal safety of American consumers, ignore past bad practices of the company involving the misuse of location data, pose a direct risk of consumer harm and constitute an unfair and deceptive trade practice subject to investigation by the Federal Trade Commission."

Katherine Tassi, managing counsel of data privacy at Uber, said in a blogpost in May that the platform "cares deeply about the privacy of our riders and drivers" and that the firm did not plan to start tracking location and accessing contacts immediately.

The new privacy policy will mean that such options are available for Uber and that if put in place customers would be forced to opt out if they did not want such information shared.

By using an opt-out rather than an opt-in system, both Epic and Open Rights Group claim that an unreasonable burden is placed on consumers.

"Most people would not expect to have their location recorded when they are not actually using an app so it's not enough to put the onus on customers to opt out if they don't want to be tracked," Killock said.

"If Uber wants to track their customers in this way, they should explicitly ask for consent and explain how the collected information will be used."

In response to a request for comment about the new changes, a spokesperson for Uber told IBTimes UK that it needed to maintain its privacy policy to "reflect changing technologies and business offerings", dismissing the complaints made by EPIC to the FTC.

"There is no basis for this complaint," the spokesperson said. "We care deeply about the privacy of our riders and driver-partners and have significantly streamlined our privacy statements in order to improve readability and transparency.

"These updated statements don't reflect a shift in our practices, they more clearly lay out the data we collect today and how it is used to provide or improve our services."