Alleging that "malpractices" in the stock market has led to its crash on the past two days, the Communist Party of India on Wednesday demanded an enquiry into the collapse and sought a heavy increase in the securities transaction tax from the present levels.

"We demand an appropriate inquiry as there are reasons to believe that malpractices, aberrations and the lack of a supervisory role by Sebi has led to such a crash," party leader Gurudas Dasgupta said.

He held Finance Minister P Chidambaram "morally responsible", along with the government's economic policies for the crumbling on the bourses.

Party General Secretary A B Bardhan demanded a hefty increase in the securities transaction tax (applicable on purchase and sale of equities), which, he said, had been reduced to a "nominal 0.1 per cent" following "pressure" from the big players in stock exchanges.

Observing that the Indian stock market is "increasingly becoming a casino", he said if such volatility continued, "there can be a big crisis, may be a hundred times more than the Harshad Mehta episode." Calling for a halt to the "senseless Sensex boom", Bardhan said when thousands of farmers commit suicide due to the acute agrarian distress, "government does not lose its sleep. But when there is a panic in the market and Sensex falls, the Finance Minister rushes in to reassure everyone."