The demonstrators chanted leader André Ventura’s name as security forces struggled to enforce social distancing guidelines against the spread of Covid-19.

Ventura, an ally of France’s Marine Le Pen and Italy’s Matteo Salvini, has floated the idea of a special anti-Covid quarantine for Portugal’s minority Roma. Ventura has seen his popularity soar and captured almost 12 percent of the vote in a presidential election in January.