French farmers set up a filter roadblock on the A340 near the Belgian border on Tuesday morning, according to federal police.
The protest is taking place on the French side of the Franco-Belgian border.
For lorry drivers, police recommend using the Couvin Nord exit at the locomotive roundabout and heading to Chimay via the N99.
The governor of Namur province, Denis Mathen, had warned on Monday evening that the protest might disrupt mobility in Belgium, particularly for lorries travelling to or from France.
Farmers are demonstrating against the EU-Mercosur free trade agreement, which received approval from most European countries on Friday.
