Employees of public transport were among the first to join the action, which is likely to disrupt the summit of EU leaders held in the Belgian capital on Monday.
Transport in the country are almost entirely paralyzed. The international high-speed trains Thalys and Eurostar from Brussels to Paris, Amsterdam, Cologne and London, have interrupted their service.
The airport of the city of Charleroi, the second in the country, is closed. The strike could also affect the functioning of the international airport of Brussels, the Belgian Pilots Association has urged its members to support the protest.
Although no major event is scheduled, the Belgian capital may be “under siege”, the strikers had blocked several entries of Brussels.
The last 24 hours general strike was held in Belgium in 1993.