The authorities said efforts were on to identify the offender.
CCTV footage surfaced on social media showing a man getting up from his seat and spraying the doors with black paint. He was seen painting a large 'X' on the door.
Caught on Kolkata Metro Railway's CCTV camera pic.twitter.com/FseizQqPRV
In the video clip, none of the passengers was seen protesting.
Metro Railway Kolkata said in a statement on Wednesday: "It has been observed that Door No.5 of Coach No. 4036 of a Metro rake (MR-409) operated on Blue Line has been defaced recently with black spray paint by a commuter. Such an act has caused damage to the aesthetic look of the coach." It has hurt the sentiment of Metro users, the statement said and urged all to refrain from repeating this incident.
"With the help of CCTV cameras installed in the rakes and stations, such activities can be recorded easily and offenders can be identified. Legal action will be initiated against any person found to be engaged in such activities," the statement added.
The authorities urged the Metro users to stop co-passengers if they indulge in such misdeeds.
Meanwhile, Kolkata Police sources said the Metro Railway authorities have approached the force to help them identify the offender.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
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