Police are looking into a minor oil spill that was detected late Sunday in sea water off the coast of Helsinki, between the Merisatama harbour on the mainland and the small island of Liuskasaari.
Fire chief Timo Ustinov from the Helsinki Rescue Department says the oil is believed to have leaked into the water from land.
Earlier another rescue official, Paul Nyberg, told Yle that the oil floating near the Kaivopuisto park shore may have come from a vessel anchored at a nearby guest harbour or from a mishap at a maritime filling station on Liuskasaari.
As of Monday evening, officials had not yet pinpointed the type of oil or how much was spilled.
Inspector Ismo Siltamäki of the Helsinki Police says it is also so far unclear what criminal charges might be brought if the culprit is identified.
Three rescue services vessels were on the scene by 11pm Sunday evening. They worked to set up over 150 metres of containment booms, or floating barriers, to keep the oil within a confined area.
The Border Guard is taking samples and rescue personnel reported a strong fuel oil smell, but as yet there is no information as to the type of oil or how it got into the sea. Officials say the nearby boat harbour has several dozen berths for visiting boaters.