Last week the group struck again, marking an escalation in a campaign of economic sabotage which one campaigner said is intended to drive the Belgian hamburger industry out of business. No other country has suffered such a sustained bout of eco-terrorism against burger bars - 10 this year - and nowhere else has the campaign been so extreme or bizarre.
In the most macabre incident, police arrived outside a McDonald's in Brussels to find what they assumed to be animal remains. Closer examination showed them to be of human origin, exhumed from a cemetery in the city's Ixelles district. The Belgium Animal Liberation Front did not claim responsibility for that attack, as it has for most others, and although three people in the city were questioned, no charges have been brought.
Last week's incident was more typical of a trend which has developed since April. Several attacks have taken place in or around Antwerp, but this time a fast food restaurant in Genk was seriously damaged by fire. Although no one has yet been hurt, the law enforcement agencies are taken aback by what is a new phenomenon in a country where meat eating is the norm. They are investigating a possible link to Britain, a stronghold of activism and the birthplace of the Animal Liberation Front.
"We have had terrorist groups in Belgium before, but I don't remember a case like this in the last 20 years," said Jos Colpin, of the public prosecutor's office in Brussels. With activists operating through cells, police face formidable difficulties in tracing the perpetrators of crimes ranging from large-scale destruction to small-scale vandalism.
Other parts of the meat industry have been attacked, including meat trucks and a cold storage unit. But the main targets have been McDonald's and Quick, the home-based company with the largest number of burger outlets in Belgium, and an expanding network in France. They have suffered all but two of the "actions" claimed by the Belgium ALF this year. Most have been arson attacks, but often, as at a Quick in Grotesteenweg Berchem near Antwerp, slogans such as "Meat Industry = Death" and "ALF" are spray- painted on walls.
Both chains are popular with shoppers, and make a point of catering for children, with specially-designed menus and play areas. That may be the very thing, however, which has put them in the activists' sights. In a statement explaining one set of attacks, Belgium ALF argued: "McDonald's makes profits from children ... Here in Belgium McDonald's have started a new campaign: on big posters with the picture from a big island full with trees stands the text: 'Everyone has the right for a piece of paradise' Meanwhile, McDeadly is cutting the rainforest!!! The bastards!!!"
Some believe that the "McLibel" trial pursued by McDonald's against two campaigners in Britain may have put the company in the firing line. According to Robin Webb, British-based spokesman for the ALF, the rationale behind the campaign is not to gain publicity but to wage economic warfare against the retailers. "The point of attacking McDonald's is economic sabotage," he argued. "It will increase their security costs and their insurance premiums, with the intent of pricing them out of the industry.
"There is a link, in as much as the Belgian ALF has made claims of responsibility to British ALF supporters, although the activists do what they do without telling any other group. The ease with which people now can communicate with each other has, I think, helped to escalate things."
The internet, and proximity to Britain, may be the key to the spate of violence. There is easy access through a website to a forum where information, including details of targets, can be exchanged. Activists are encouraged to restrict the most sensitive of contacts to e-mail addresses designed to be difficult for the authorities to trace.
Neither McDonald's nor Quick were available for comment, perhaps worried about retaliation. There is, however, no doubting their alarm. As one fast food worker put it: "We have to take these organisations very seriously. They are dangerous."