On Monday, French winemakers attacked at least five trucks carrying Spanish wine at a toll barrier in Le Boulou, near the border of Spain.

At least 90,000 bottles of red and white wine were destroyed, while the words “vin non conforme,” non-compliant wine, were written on the sides of the trucks. According to the Telegraph, local French authorities “looked on,” but did not intervene.

The farmers were protesting what they described as “unfair competition” from Spain, an issue that has not only affected French winemakers but also producers of other agricultural foods like dairy and meat products. Last summer, French farmers attacked trucks carrying Spanish produce, prompting anger from Madrid, Spain’s capital.

Shortly after the attack this week, a French regional representative was reportedly filmed “calmly promising” to investigate French winemakers’ accusations that fraudulent Spanish wine was being imported into France. Spanish wine producers are accused of mixing their wines with wines from South America, and some are believed to be labeling their wines as “Made in France.”

Industry reports recently showed that France has become the top buyer of Spanish wine, purchasing 580 million liters in 2014, and Italy has become the world’s biggest wine producer with 4,900 million liters per year, beating out France’s 4,700 million liters.

On Wednesday, Spain summoned the French ambassador and called the attack a “flagrant violation of various basic principles” of the European Union. The incident was also reported to the European Commission.

“These incidents, which are occurring all too frequently, are grounds for concern for the government of Spain," the Spanish foreign ministry said in a statement. “Spain has already officially passed on its protest to the French authorities, and urges them to adopt all appropriate measures to guarantee, with absolute security, the free movement of people and goods, one of the basic principles of the European Union.”