He said this at a joint briefing with Ukrainian Foreign Minister Pavlo Klimkin in Mariupol on Wednesday, an Ukrinform correspondent reports.
"A real ceasefire must be the basis for the effective work of the OSCE Special Monitoring Mission. This should also be the basis for holding free and fair elections in Donbas," Kurtz said.
He added that he was dissatisfied with the current status quo in Donbas, but he saw no alternative to the Minsk agreements.
"We should continue to hold negotiations, and the Minsk agreements are the only basis, the only document which we can use for this," he said.