A similar operation last Friday found 13 drivers in the same position.

The Portuguese taxi federation has been criticising the “inaction of the (police) responsible for enforcing the law against the illegal transport of passengers”.

The law, which came into force in November, regulates access to the activity and the taxi transport market and bolsters “dissuasion measures” in the sector as it increased the fines.

Operating a Uber or Cabify vehicle without a licence can mean a fine of €2,000 to €4,500 for an individual and €5,000 to €15,000 for a company.