"The Prime Minister's statement is unsatisfactory and we want an immediate discussion in Parliament" senior party leader Sitaram Yechury told reporters outside Parliament.
Demanding cancellation of all allotments and a wide-ranging probe into the entire gamut of the CAG's findings, Yechury said the investigation into the issue should lead to fixing responsibility and prosecute all those found guilty "however high position they may hold".
"While all coal block allocations should be cancelled and a wide-ranging probe ordered into the CAG's findings, the government should also take steps to recover the losses suffered by the public exchequer", he said.
The CAG Report had claimed that allocations of coal blocks to private companies had resulted in their benefiting to the tune of Rs 1.86 lakh crores.
The CPI(M) has asked its units across the country to conduct a campaign on the "large-scale corruption" in the matter, hold demonstrations, rallies and protest meetings between September three and five.