Two passengers were left injured, one seriously, after their coats became trapped in Tube doors as Northern Line trains pulled away from platforms.
A probe has been launched by the Government after two separate but similar "trap and drag accidents" just a month apart at Archway and Chalk Farm stations.
One passenger was seriously injured after their coat got stuck in the doors of a northbound train at Archway at 3.50pm on February 18.
They were pulled to the ground and dragged for two metres along the platform until their coat came free from the door.
The passenger and their friend both fell to the floor during the incident, with the passenger sustaining a serious injury - a preliminary report into the circumstances said.
The train eventually came to a stop after travelling for about 20 metres.
The second trap and drag accident came when another person got their coat stuck in the doors of a southbound Northern Line train at Chalk Farm station.
This time the passenger was dragged for just under 20 metres - until their coat became free of the doors at around 11pm on April 20 this year.
The passenger fell onto the platform during the accident and sustained "minor injuries".
The train did not stop and continued on its journey.
A probe launched into the accidents will consider the actions of those involved, any risks to passengers boarding or alighting on the Underground, post-incident management and other management factors.
A Government spokesperson said: "Our investigation is independent of any investigation by the railway industry or by the industry's regulator, the Office of Rail and Road.
"We will publish our findings, including any recommendations to improve safety, at the conclusion of our investigation. This report will be available on our website."
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