KYIV, Sept 28 - NATO and the European Union said on Wednesday that the leaks in two major pipelines in the Baltic Sea were caused by "sabotage," and vowed the "strongest possible response," pledging to step up the protection of critical European infrastructure without accusing anyone of being behind the incident.

The Nord Stream 1 and 2 pipelines burst in several locations in the exclusive economic zones of Denmark and Sweden while neither of them was in operation amid an energy standoff between Russia and Europe.