"You know better how Trinamool's mafia raj is continuing in coal mines here. Trinamool leaders are making money while mines workers are deprived of their remuneration," Modi said at an election rally in Bankura.
He said people sacrificed their lives in a bid to restore democracy. "Their sacrifice will not go in vain," Modi told a rally in Purulia later.
"Purulia is endowed with natural resources. You are sitting on black gold. Till now, successive governments in the state have established mafia raj here. In fact, the Trinamool government has made mafias a part of its activities," he alleged.
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Hitting out at Modi, Banerjee said: "You said Trinamool's candidates are coal mafias. I challenge you. I will withdraw the party's nominees in all 42 Lok Sabha constituencies in West Bengal if you are able to prove such allegations against any of our candidates," she told an election rally.
"If you are lying, you have to hold your ears and do a hundred sit ups before public," she said.
Coal comes under the purview of the central government and BJP leaders become agents of coal transactions, she alleged.
"I have a pen drive. If I make it public, documents of coal mafias and cow smuggling would be out," she threatened Modi.
Modi and Banerjee were engaged in a vicious war of words in their poll rallies in the recent past, heating up the electoral battle during the ongoing Lok Sabha elections.
(With inputs from IANS)