Uber drivers in the U.K. are filing a lawsuit against the company over allegations the firm has continuously broken European data protection laws.

Four drivers are taking legal action against the ride-hailing giant, claiming the company is "failing to honour its obligations" under the EU's General Data Protection Regulation (GDPR) legislation.

Under GDPR rules, individuals have the right to access personal data held by any company — even their employer. Companies have one month to respond to a request for data, whether it is made verbally or in writing.

In a letter sent to Uber this week, the drivers claimed it had breached the regulations by repeatedly failing to provide them with information, such as the duration of time they spent logged onto the platform, their individual GPS data, and trip ratings.

Speaking to CNBC on the phone Friday, James Farrar — the driver jointly leading the case — said he had been "back and forth" with Uber over his data since July. He alleged that Uber was withholding GPS data that showed the "dead mileage" he accrued on the job, making impossible for him to calculate his hourly wage.

"I can only calculate the hourly pay that they want me to," he said. "(They've given me) trip information that includes start to finish location points, fares and durations for individual journeys, but providing all of my GPS data and log on and off times would allow me to calculate my hourly pay."

Farrar added that he was "totally" sure Uber was purposely withholding the information.

"Giving us the data will help drivers understand if they can get a better deal or not," he told CNBC. "I also see lots of drivers being deactivated from the platform for little or no reason and because they're self-employed there's no need for due process – if we're given access to our data we can begin to challenge that."

Farrar is one of the drivers currently embroiled in a separate case against Uber, in which U.K. drivers are fighting to be legally acknowledged as employees of the company and therefore entitled to rights such as paid holiday and a minimum wage.

In a statement emailed to CNBC, an Uber spokesperson said: "Our privacy team works hard to provide as much information as we can, including explanations when we can't provide certain data (because) the data doesn't exist or disclosing it would infringe on the rights of another person under GDPR. Under the law, U.K. citizens also have the right to escalate their concerns by contacting Uber's Data Protection Officer or the ICO for additional review."

Ravi Naik, one of the lawyers representing the drivers, said in a press release Thursday that his clients had made "numerous requests" for their data.

"It is regrettable that our clients have had to seek legal advice to assert their rights, rather than Uber simply complying with the law. How they now respond will be a stress-test of Uber's commitment to data protection," he said.

The legal action is being backed by Worker Info Exchange, an organization founded by Farrar that campaigns for workers to be given access to data collected by their employers.