From April 8, private hire vehicle (PHV) drivers will no longer be exempt from the £12.50 ($16.55) daily congestion charge to drive in central London under mayor Sadiq Khan's new rules.

PHV drivers, including drivers working for Uber and other ride sharing services, are now taking legal action against the Mayor's office, claiming that exempting black cab drivers and not PHV drivers from the charge is "discrimination," the BBC reports.

This is due to the fact that 94 percent of London's roughly 114,000 PHV drivers are from black, Asian and minority ethnic (BAME) backgrounds, and many are from "deprived areas," according to a Transport for London report. Black cab drivers are overwhelmingly white British, the report states.

Uber driver Abdurzak Hadi told the BBC that the charge means that he is "punished for coming to work." "This is a tax on poor drivers," Hadi told the BBC.

Per the BBC, Uber drivers will have to pay this charge themselves, since Uber decides the rates of rides, preventing drivers from passing the extra charge on to passengers.

This is indirect discrimination against ethnic minority drivers, The Independent Workers' Union of Great Britain (IWGB) claims. They are now calling on a a judicial review of the mayor's decision, per the BBC.

Indirect discrimination is covered by the Equality Act 2010. Per the Citizens Advice bureau, indirect discrimination is defined as when a practice, policy or rule which applies to everyone in the same way has a worse effect on some than others.

Khan's office told the BBC that they aren't "prepared to ignore the damaging impact this has on congestion and increasing air pollution." Congestion has a "crippling" effect on the capital, and is causing a "major public health crisis" due to air pollution, the mayor's office added.

"Removing the congestion charge exemption for private hire vehicles is a key part of our plans to both reduce congestion and to protect Londoners from harmful emissions from polluting vehicles," Khan's office said.