The Swedish Coast Guard is using sonar to search in the area of the Koster Fjord where bubbling oil has been discovered.

“It is a depth of 50 and 60 meters right there, but there is a lot of depth variation in the area. Just a little bit away from there it’s 160 meters deep,” Peter Lindquist, spokesperson for the Maritime Rescue Coordination Centre, told TT.

Two fishing boats participating in the search detected an unknown echo from the sea bottom using sonar.

“Something is down there at 108 meters. We can reach it with our remote-controlled underwater vessel,” Lars Belfrage, commander on duty at the Coast Guard, told TT.

The search conditions have also improved greatly and the entire area will be searched again.

“Yesterday it wasn’t easy to see everything. Theoretically, someone may have made it to land and is on an islet, so we will continue the search,” Lindquist said.

The first distress signal came in at around 6 am on Friday morning off the coasts near the Swedish town of Strömstad. During the day, aircraft, helicopters and several boats searched for survivors without any success.

The weather conditions were difficult, with powerful wind and stormy seas. The only traces of the Langeland that were found were the emergency transmitter, several life vests, an empty life raft, several oil drums and a single refridgerator.

On Saturday morning, a rescue helicopters was dispatched to the scene of the accident in hopes of finding survivors. Two coast guard ships will also go out together with local fishermen to search for the vessel with sonar.

The Langeland, which is 70 metres long and weighs 2,500 tonnes, was loaded with stone and was on en route to Moss in Norway. The cause of the accident is unknown. One theory is that the cargo came loose due to the inclement weather, causing the ship to become lopsided.

According to the Swedish coastguard, the Langeland has previously run into trouble in Sweden, including several major concerns about safety onboard. Following a February 2007 inspection, the ship sequestered in the Landskrona harbour for several days due to major safety violations. The same summer, 13 violations were reported during an inspection in Gothenburg.