Tens of thousands protested in Brussels on Tuesday against Prime Minister Bart de Wever’s proposed austerity measures, prompting police to fire tear gas to disperse the crowds.

Minor clashes occurred as demonstrators set off flares and smoke bombs, played drums and horns, and choked major roads and transportation hubs.

The protest, organized by Belgium’s three major trade unions, also coincided with nationwide strikes targeting cuts to pensions and healthcare.

Organizers estimated 150,000 participants, while police put the number at 80,000, the AP has reported.

De Wever, a Flemish nationalist who took office in February, aims to reduce spending to address Belgium’s rising budget deficit, projected to reach 6.5% of GDP by 2030.