European Commission chief Ursula von der Leyen has threatened the "strongest possible response" against Vladimir Putin for the "deliberate" sabotage of the Nordstream gas pipeline.

Gas is now leaking into the Baltic from three holes, scientists have confirmed, while chronic safety concerns have led to a five-mile exclusion zone being imposed around the affected area.

Ms von der Leyen said she had spoken to the Danish Prime Minister about the "sabotage action" and stressed the importance of investigating the incidents.