A diplomat says that representatives of three European countries threatening to reimpose U.N. sanctions on Iran over its nuclear program failed to agree with their Iranian counterpart on how to avoid the move,

Britain, France and Germany will begin the process of reimposing U.N. sanctions on Iran at the U.N. Security Council on Thursday, two European diplomats said. The trio, known as the E3, met Iran on Tuesday to try to revive diplomacy over the nuclear programme before they lose the ability in mid-October to restore sanctions on Tehran that were lifted under a 2015 nuclear accord with world powers.

Britain, France and Germany plan to jointly notify the U.N. Security Council that Iran is in “significant” violation of the 2015 nuclear deal.