The Swedish military said Tuesday that a photograph believed to show a foreign submarine in the sea off Stockholm last October was in fact of a civilian vessel.
"There is no submarine" in the October 31 photo, "it's a civilian boat," military spokesman Jesper Tengroth told AFP.
The military carried out in-depth analysis on the photograph, he said, but disclosed no other details.
The Swedish military still insists, however, that there was an incursion into its waters by a mystery vessel some time between October 17-24.
Sweden launched a huge hunt for a foreign submarine, suspected to be Russian, in the Stockholm archipelago over the eight-day period in October.
The military subsequently confirmed that "a mini submarine" had violated its territorial waters, but was never able to establish the vessel's nationality.
The photograph in question, which shows an object from afar which could be a submarine tower, was taken a week later, on October 31, when the hunt had already been called off.
The photo was shot in an area about two miles (three kilometres) from the city centre, close to busy ferry traffic lanes.
The October 31 photo was taken by a retired naval officer, Sven Olof Kviman, who took part in Sweden's hunts for Russian subs in the 1980s and 1990s.
An amateur photo made available on October 19, 2014 by Swedish Defence shows a dark object in the sea.
He alerted authorities after watching the vessel for several minutes with binoculars with his wife, he told Swedish daily Dagens Nyheter.
He said he doubts the military's conclusions.
"It's absolutely impossible that we saw incorrectly, in such case my wife and I are both colour blind... I saw the sub when it surfaced... It's always hard to judge size but it was about 20 or 30 metres (65-98 feet) long," he told the paper.
According to the military, the civilian boat in question was a 10.5 metre white fibreglass boat.
During and after the failed hunt, the Swedish press questioned whether the country was able to defend itself from territorial violations following years of defence budget cutbacks.
In March, the Swedish government announced a 6.2 billion-kronor ($702-million, 665-million-euro) hike in defence spending largely focused on upgrading its capacity to detect and intercept submarines.