Three ships from the Swedish Coast Guard are working to contain as much of the spill as possible, whose total area was unclear. The Coast Guard was set to deploy booms to trap the oil and then pump it up.
The clean-up work was hampered however by high winds and waves that threaten to pull apart the spill.
"There are streaks on the water and there is a strong smell of diesel," according to Per-Erik Söderström at the Swedish Coast Guard.
The ship Kertu left from Södertälje just before midnight on Tuesday with the destination of Kokkola, Finland. The Coast Guard was notified of the accident just before 5 a.m. Wednesday.