Officials said four people were killed in alleged clashes between Trinamool and BJP supporters.
The National Human Rights Commission (NHRC) ordered a spot inquiry following reports of post-poll violence from several districts in West Bengal.
The state was in the throes of widespread violence on Monday that allegedly left several BJP workers dead and injured in clashes, and shops being looted, prompting the centre to seek a factual report from the government on incidents of attack on opposition workers.
Officials said four people were also killed in alleged clashes between Trinamool and BJP supporters in Burdwan district on Sunday and Monday.
The Trinamool claimed three of them were its supporters.
The NHRC said it has come across several media reports published in newspapers on Tuesday regarding the death of some people in the alleged post-poll violence in West Bengal on Monday.
Political workers allegedly clashed with each other, party offices were torched down and some homes were ransacked and valuables also looted, the body said.
District administration and local law and order enforcement agencies appear not to have acted to stop such violation of human rights of the affected persons, it noted.
"Considering as a fit case of alleged violation of Right to Life of the innocent citizens, the commission has today taken suo-motu cognizance of the matter and has requested its DIG (Investigation) to constitute a team of officers of the Investigation Division of the commission to conduct an on-the-spot fact-finding investigation and to submit a report at the earliest, preferably within two weeks," it said in a statement.
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