STOCKHOLM: Sweden’s navy widened the search on Monday for a suspected foreign submarine as speculation mounted over the origin of the mystery vessel.

The search was being extended southwards to the open sea about 70 km(44 miles) southeast of Stockholm, as Swedish Prime Minister Stefan Loefven said that more military exercises were being carried out in the Baltic Sea.

“There’s an increase in military exercises from both the Russian and the NATO side,” Prime Minister Stefan Loefven said, speaking at a press conference in Helsinki.

“There’s no reason for exaggerated concern here but obviously we are aware of what’s happening in the Baltic Sea because it’s our neighborhood.”