Tens of thousands of people have taken to the streets in Brussels as part of a national strike over government reforms and spending cuts that has brought flights to a halt and severely disrupted public transport.

Belgium's three big unions are protesting over pensions and other measures by Prime Minister Bart de Wever's centre-right government aimed at cutting the budget deficit.

There were no services at Belgium's second biggest airport at Charleroi, and all departures and many of the arrivals were cancelled at Brussels Airport. Although trains were running, most buses, trams and underground trains in the capital ground to a halt.

Shipping at Europe's second biggest port Antwerp was suspended until Wednesday because of understaffing, leading to over 100 ships waiting in the North Sea to dock at three ports. By midday, police reported around 80,000 protesters had joined the demonstration in the capital.

Public sector workers voiced concerns over austerity measures and the government’s increasingly right-leaning policies. They walked through Brussels while wearing the colors of their respective unions. Key issues include a proposed increase in the working years required before pension eligibility and the potential elimination of special provisions for certain professions like military and railway workers.

De Wever's government has also discussed limiting unemployment benefits to two years and announced further budget cuts for the coming year. Protesters articulated worries about the implications for their futures and those of their children, emphasizing the need for unity against perceived unjust reforms. While the protests remained predominantly peaceful, there were reports of vandalism and clashes with police, reflecting the heightened tensions surrounding these significant policy changes.