One of the trains hit the side of the other at a point where two tracks joined together. Both were travelling at low speed, around 40 kilometres per hour, when the accident happened in Helsingborg.
"The passengers have been escorted off the train and taken to a gathering point where any injured people will be picked up," said a police press spokesperson.
One of the trains had around 150 people on board while the other was empty, but rescue services said no-one had been seriously injured.
"There are a few moderately injured people," Ronnie Lundgren from the local rescue services said. "It's neck and back pain that some people have reported."
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The accident, which took place at around 7pm, led to delays and cancelled trains throughout Thursday evening. No trains were able to stop or pass through Helsingborg, leading to diversions, including on the Öresundtåg route between Sweden and Denmark.
By 10pm however, two of the four tracks were reopened. Trains were running on a slightly reduced service on Friday morning and expected to return to the normal service by around midday. Information about affected journeys can be found here.
It is not yet clear what caused the collision. Skånetrafiken, the regional public transport authority, has asked passengers who were on the affected train to contact the company regarding possible compensation.