New Delhi, Aug. 3 -- TALLINN - Estonian Prime Minister Kristen Michal said Sunday that Spain's decision to legalize the status of hundreds of thousands of undocumented residents had created measurable incentives for illegal migration across the Mediterranean, and that the renewed surge of arrivals at Spain's Ceuta enclave was the foreseeable consequence of a policy that sent the wrong signal at the worst possible moment. His remarks sharpened Tallinn's position in a growing intra-European dispute over whether southern member states were undermining the collective border enforcement posture the EU had been trying to project.

Michal, speaking after talks with Nordic and Baltic counterparts, did not name Prime Minister Pedro Sanchez directl...