Oslo has officially attributed the cyberattack to its neighbour

Norway spy chief blames Russian hackers for dam sabotage in April.

According to Reuters Russian hackers briefly took control of a dam in Norway earlier this year, the head of the Nordic country's counter-intelligence agency said on Wednesday, the first time Oslo has officially attributed the cyberattack to its neighbour.

While in command of the dam in Bremanger, western Norway, on April 7, the hackers opened a flood gate and released 500 litres (132 gallons) of water per second for four hours before the attack was detected and stopped, authorities previously said.