Moscow: The Kremlin said Tuesday it was "extremely concerned" about reported leaks on Russia's Nord Stream gas pipeline to Europe and its twin pipeline Nord Stream 2.

"This is a completely unprecedented situation that requires urgent investigation. We are extremely concerned about this news," Kremlin spokesman Dmitry Peskov told reporters.

Asked by reporters whether it could be an act of sabotage, Peskov said: "it is impossible to exclude any options".

"Obviously there is some kind of damage to the pipe, as for what caused it -- before there are results of the investigations, no option can be ruled out," he added.

Scandinavian authorities said on Tuesday that two leaks had been identified on the Nord Stream 1 pipeline in the Baltic Sea -- one in the Danish economic zone and the other in Sweden's -- hours after a drop in pressure was reported on Nord Stream 2.

Built in parallel to the Nord Stream 1 pipeline, Nord Stream 2 was intended to double the capacity for Russian gas imports to Germany.

But Berlin blocked newly completed Nord Stream 2 in the days before Russia sent troops to pro-Western Ukraine.