If the bomb had exploded it would have caused serious damage, said police spokesperson Marie-Louise Nilsson to TT.
Police do not know whether the device was to be used on the train, or if it was being transported somewhere and forgotten, or left there intentionally.
When the train arrived at the station in central Södertälje there was a police car parked outside.
“It could be the case that someone saw the police car and didn’t want to go past it with the bag. But that’s just speculation,” said Marie-Louise Nilsson.
The plastic bag with suspicious contents was discovered on the train by a guard, who carried the bag off the carriage, put it in a sandbox near the station and called the police.
The station and bus terminal in Södertälje were evacuated and cordoned off while bomb technicians examined and removed the bag. By early evening the cordon was lifted.
After further investigation the police technicians confirmed that the bag contained explosive material and an explosive capsule.
“It’s explosive of the dynamex type,” said Nilsson.
There was no detonator, such as a battery, in the bag, but police said there was a risk that it could have exploded anyway. The device would have had a blast effect of around ten metres.
“If you put the same amount of dynamex in a metal container you would get a blast effect of 200 to 300 metres,” said Marie-Louise Nilsson.
Police said they are not aware of any threats made in connection with the train bomb.