On Wednesday, the Swedish Prosecutor's Office announced the termination of its investigation into the blasts, ruling it does not belong to its jurisdiction. Sweden has handed the materials on the issue to Germany for its investigation into the matter, Swedish public prosecutor Mats Ljungqvist said.
"Hundreds of days have been passed, and no serious investigation has taken place yet. No details have been revealed yet. And I think it's unacceptable," Szijjarto said.
The minister called it "a terrorist attack against a strategic infrastructure in Europe."
"An attack against the safe supply of energy of ours, which is a strategic issue, and the matter of European security. And the fact that no investigation has taken place is very irresponsible and from our perspective, it's really unacceptable. Therefore we urge authorities, be them national or international to take the seriously," Szijjarto said.