Swedish police have opened an investigation into suspected sabotage after power cables to a pump supplying the Baltic Sea island of Gotland with water had been disconnected intentionally.

Gotland is Sweden’s largest island and is 190 miles from where Russia’s Baltic fleet is based and is seen as a key territory for Nato.

The island was briefly occupied by Russia in 1808, and more recently Micael Bydén, Sweden’s former defence chief, said Vladimir Putin, the Russian president, had had “both eyes on it”.

According to police, technicians had responded to a fault alarm from Gotland’s water and sewage unit on Sunday.