Transport Malta officials carried out random inspections on Y-plate vehicles on Thursday night, impounding 12 cars that were operating "without a permit".
The action comes after almost a fifth of all Y-plate cabs in operation were ordered off the roads in a major clampdown by the government.
Malta’s three ride-hailing platforms – Bolt, eCabs and Uber – received an official TM notice earlier this week ordering them to block almost 900 cabs from their apps in a bid to crack down on irregular on-street parking.
Operators of these cabs did not adhere to the Public Service Garage policy – which obliges all cabs to be garaged at night or when not in use.
On Friday TM said that while ride-hailing apps had suspended every vehicle it had identified, 12 Y-plate vehicles were impounded on Thursday night after being found to be operating without a permit.
In a Facebook post, Transport Minister Chris Bonett said the impounded vehicles had been found to be outside "the parameters of regulations".
"We have made it clear that abuse must stop. This principle will continue to guide our work in this sector," he added.