Any Muslim who can afford it must sacrifice a sheep or goat during the Offer Feast, which lasts 4 days. The problem starts when most people celebrate the holiday at home, and due to various health concerns, home slaughtering is illegal in many countries.
In Belgium, in an attempt to try and combat illegal slaughtering, authorities are setting up slaughterhouses that can deal with the sudden large demand. About 4000 sheep were slaughtered in such slaughterhouses yesterday, but an estimated 13,000 sheep were slaughtered in private homes.
In France where somewhere between 150,000 and 180,000 sheep are slaughtered during the holiday, usually illegally, a novel solution has been set up. A supermarket chain (Carrefour) is offering ready meat which has been sacrificed according to the ritual requirements. Though this move is accepted by the Muslim leaders, it is actually a step in separating between the original intent (showing faithfulness) and the actual deed (buying/eating slaughtered meat).
Sources: Islam Online (English), Expatica (English), Trouw (Dutch)