France, Dec. 18 -- Hundreds of tractors began rolling into the European quarter of the EU capital on Thursday morning, ahead of a high-stakes summit among European Union leaders.

Convoys of farmers had arrived overnight, coming primarily from the Netherlands - scene of strong mobilisation among farmers in recent years - but also from Belgium and northern France.

French and Belgian farmers also began demonstrating on Wednesday around Bierset airport, near Liege, Belgium - a symbolic gathering place, as the airport is a logistics hub and could be the gateway for South American agricultural imports in the future.

Farmers, particularly in France, worry that the Mercosur deal- which will be discussed at the EU leaders meeting - will see the...