NATO believes that the Nord Stream 1 and Nord Stream 2 gas pipelines have been damaged as a result of sabotage.

"The damage to the Nord Stream 1 and Nord Stream 2 pipelines in international waters in the Baltic Sea is of deep concern. All currently available information indicates that this is the result of deliberate, reckless, and irresponsible acts of sabotage," NATO said in a statement on Thursday.

"These leaks are causing risks to shipping and substantial environmental damage. We support the investigations underway to determine the origin of the damage," the statement said.