The cargo ship Kertu, sailing under the Maltese flag but belonging to Estonian company Hansa Shipping, ran into rocks in Stockholm's archipelago on Wednesday morning. The accident caused an oil spill, the extent of which is not yet known.

There were fears that the ship, which was carrying 52 tonnes of oil, could sink, but the situation is no longer critical, reports Swedish TV channel SVT.

The ship ran into trouble early Wednesday morning. The Swedish coast guard received an emergency call around 5:00. Two environmental protection vessels were immediately dispatched to the crash site, these were joined by other emergency teams later on.

At least one of the ship's tanks was damaged and was leaking oil. However, Jonny Åberg from the Swedish coast guard told The Local that it is too early to say how much damage has been done to the local wildlife.

He added that staff on the ship were working hard to transfer oil from the leaking tank into another container on the vessel.

Weather conditions complicated the rescue operation. "The problem with strong winds is that the oil mixes with water more. It is also difficult to get on board. But we believe that the wind will subside during the day," Åberg said.

According to the Finnish Yle news, the ship was moving on its own by Wednesday evening.

The Kertu was built in 1996; it is 85 meters long and 13 meters wide. It was on its way to Kokkola port in Finland.