On Sunday, around 200 protesters destroyed six hectares of maize at a farm near the city of Toulouse, the first time a commercial operation had been targeted. Previous attacks by anti-GMO protesters had been on test fields of new varieties.

The GMO maize was due to be shipped to Spain, where it is incorporated into animal feed.

"This was a first attack on commercially grown maize. Six hectares were destroyed," Bove told Reuters.

Bove, who has long campaigned against GMO crops, globalisation and fast food spent six weeks in jail in 2003 for smashing up a McDonald's restaurant. He was sentenced to four months in prison in November for destroying a GMO maize field.

In June, he announced his intention to run as a candidate in France's presidential elections in 2007.

The latest attack followed a Paris court ruling last week, ordering environmental group Greenpeace to remove the locations of commercial GMO fields in France from its website.

There were also two other attacks on test fields in the same area at the weekend. Five protesters have been detained.

Farm minister Dominique Bussereau strongly condemned what he termed "these acts of vandalism".

Commercial GMO maize growing is slowly spreading in France with some 5,000 hectares sown this year against 493 in 2005.

There are more than 1.5 million hectares sown to traditional maize varieties.