According to the emergency services in Gothenburg, between 500 and 600 litres of oil spilled from the train after it hit an object in the early hours of Sunday.
"We are on the ground working with a decontamination firm," Lars Jostelius of the emergency services told local newspaper Göteborgs Posten (GP) on Sunday morning.
Initially, local police did not want to specify what kind of object it was, but said they were not ruling out sabotage. In other words, one person or a group of people could have deliberately placed the object on the tracks.
The Swedish Transport Administration (Trafikverket) later confirmed that the object was a garbage bin.
Incidents where an object is placed on train tracks are labelled "infrastructure sabotage" by the Transport Administration.
The fact that someone could have deliberately placed the garbage bin on the tracks is regarded as very serious, said the Transport Administration.
"There could be serious accidents and there are costs involved for society when a train is stalled and has to be repaired," Bodil Sonesson, a Swedish Transport Administration spokeswoman, told news agency TT.
There were no passengers on board the train when it hit the garbage bin and no reported injuries.
The train traffic was confined to a single track while the leaking train was being removed in an extensive cleanup operation.
This led to delays of between 10 and 15 minutes up until lunchtime on Sunday.
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