LONDON — Uber is facing legal action over its use of facial recognition software that allegedly discriminates against people of color.

Three former workers have launched employment tribunal claims in the United Kingdom against Uber, accusing the company of unfair dismissal after its facial recognition system failed to identify them.

The legal claims were launched this week with help from two unions, the Independent Workers Union of Great Britain (IWGB) and the App Drivers & Couriers Union (ADCU). Union officials and Uber drivers staged a protest outside the company's offices in London on Wednesday.

The unions allege that Uber's facial recognition system, which is used to verify the identity of drivers and couriers, is not able to effectively identify people with darker skin. Some drivers say their Uber (UBER) accounts were terminated because the technology does not work.

"Hundreds of drivers and couriers who served through the pandemic have lost their jobs without any due process or evidence of wrongdoing," IWGB general secretary Henry Chango Lopez said in a statement.

"Uber must urgently scrap this racist algorithm and reinstate all the drivers it has unfairly terminated."

According to Uber's website, workers can chose to have their identity verified either by photo comparison software developed by Microsoft, or by human reviewers. A spokesperson said Thursday that its "Real-Time ID Check" system "is designed to protect the safety and security of everyone who uses the Uber app."

"The system includes robust human review to make sure that this algorithm is not making decisions about someone's livelihood in a vacuum, without oversight," the Uber spokesperson added.

Studies have shown that commercial facial recognition algorithms frequently misidentify minorities and people of color. Microsoft said last year that it would not sell facial recognition technology to police departments in the United States, at least until there is a federal law to regulate the technology.

A spokesperson for Microsoft (MSFT) declined to comment on the Uber allegations, "given this is an ongoing legal case."

IWGB president Alex Marshall told CNN Business that discrimination is widespread. According to the union's research, roughly 20% of darker-skinned female faces and 5% of darker-skinned male faces are not recognized by the algorithm.

The vast majority of Uber drivers and couriers in London are minorities, Marshall said. "For too long companies like Uber and others in the gig economy have had the luxury of firing people at the click of a button," he added.

Earlier this year, the UK Supreme Court upheld a ruling that Uber drivers should be classified as workers and not independent contractors.

The decision delivered a major blow to the company's business model in one of its most important markets, opening the door for drivers to claim more benefits. — CNN Business