Italian police are trying to figure out who sent a letter containing an explosive powder to Europe’s food safety agency. A bomb squad earlier this week blew up the letter, which was addressed to a scientist who works on genetically modified organisms (GMOs). The incident comes amid an ongoing and acrimonious debate over European regulation of GM crops and foods.

The suspicious letter arrived at the headquarters of the European Food Safety Authority (EFSA) in Parma, Italy, on 7 June. It “did not seem to conform to the rest of the items that we usually receive,” an EFSA spokesperson told Science Insider. Police say an inspection revealed it contained enough gunpowder inside to injure the hands and face of someone who opened it. Officials declined to identify the addressee, except to say it is a scientist who serves as an external adviser to the agency. No person or group has claimed responsibility for the letter, and it is not clear where it originated.

EFSA, created by the European Union in 2002, is charged with a wide range of tasks, including helping European governments assess the safety of GMOs. The agency has been a target of anti-GMO demonstrators, but “is neither in favor nor against GMOs. Every case is evaluated singularly,” the EFSA spokesperson says. And the agency is pleased that “all the security procedures worked extremely efficiently and promptly under the circumstances,” she says.

The European Union has approved the planting of just one GM crop— a variety of corn known as MON 810. Each member state must also approve planting, however, and in 2013 Italy barred cultivation of MON 810, as well as barring field trials of experimental GM crops.