Underwater activity has been confirmed, a submarine has been ruled out

More than 200 troops, ships and helicopters now called from a

Swedish military has called off the search for a 'Russian underwater vessel' thought to have been lurking in the Stockholm archipelago, after admitting that it was 'definitely not' a submarine.

Navy top brass has today been forced to concede that although 'underwater activity' is confirmed, the military has ruled out the possibility that it could have been a Russian sub.

This comes after Moscow blasted the hunt as 'groundless actions by the Swedish military, based on a Cold War-rhetoric'.

No Russian winter: A Swedish minesweeper and a guard boat in Namdo Bay, as the military calls off the search for a suspected Russian submarine in the Baltic Sea

The week-long hunt has involved more than 200 troops, stealth ships and helicopters which have been scouring the waters off Stockholm since last Friday.

The Swedish military's search for a 'foreign underwater activity' in the Baltic Sea has been the country's biggest military mobilisation since the Cold War.

At a press conference this morning, the military confirmed that there had been some form of underwater activity, but that a submarine has been ruled out as the water where the activity took place is too shallow.

The military has not been able to prove ‘type of vessel, nationality or activity,’ Rear Admiral Anders Grenstad said.

'There has been a suspected underwater action which is completely unacceptable.'

Calling it off: Rear Admiral Anders Grenstad, pictured earlier this week, said today that the military has been able to confirm underwater activity but that it was definitely not a submarine

Protecting borders: More than 200 troops, stealth ships and helicopters which have been scouring the waters off Stockholm since last Friday in search for the 'Russian submarine'

Rear Admiral Grenstad added: 'It is our conclusion that remaining in the archipelago would not give us more information. That would take weeks.'

He added that although underwater action has been confirmed, the vessel has now left Swedish territory, but some troops will remain to observe the area

The military had received what it described as five credible reports from the general public regarding activity by foreign submarines or divers using an underwater vehicle.

Moscow has denied the reports, refuting claims that any Russian vessels have been involved.

'These baseless actions by the Swedish military, based on a Cold War-rhetoric, will only lead to increased tension in the region,' major-general Igor Konasjenkov told local reporters today.

Is this it? This grainy amateur photo showing a mysterious vessel in Stockholm's archipelago was released by the Swedish military during the hunt

Some observations have been made during the search, but have been deemed of lesser note, something which the military believes may have been due to a delay in taking action.

'It is partly because we have come in at a late stage,' Jesper Tengroth, military press officer told Aftonbladet when questioned why nothing has been found.

'When we get the information [from the general public], the suspects have already been there.'

The vessels were unidentified, but during the 1980s the Swedish navy from time to time hunted suspected Soviet submarines in its waters

The incident heightened tensions in a region where governments are increasingly worried about Russian assertiveness since the Ukraine crisis.