Almost 1,000 minicab drivers are said to have joined a protest against congestion charges they claim will cut their take-home pay by up to 25%.
The demonstration in central London on Monday was called by the Independent Workers Union of Great Britain which claims the charge is a "tax on the poor" and will do little to reduce congestion in the capital.
The daily charge of £11.50 will have to be paid by private hire drivers, such as those working for Uber, from April.
The union said roads outside Transport for London's offices were blocked by the demonstration, which it vowed to repeat every Monday.
Spokesman James Farrar said the protest showed how angry drivers were about the extension of the congestion charge.
The ball is now in TfL's court as we have raised our collective voices and stand united against this unjust and regressive tax on the poor.
Bold action is required to tackle London's public health crisis. More than 9,000 deaths are linked to air quality every year. The private hire trade, along with all road users, have a central role in reducing the filthy fumes circulating in our city. The changes to the congestion charge will contribute to fewer vehicles driving where pollution is most concentrated while ensuring the cleanest minicabs or those that are wheelchair accessible continue to enter the zone without paying a charge. The changes to the congestion charge and the introduction of the Ultra Low Emission Zone in April will significantly benefit the health of all Londoners, including drivers.