Nothing was done without the knowledge of the states, including those ruled by the opposition, Rural Development Minister Jairam Ramesh told reporters.
"Cancellation of coal blocks en masse is impossible... nothing was done without the knowledge of the states, including those ruled by the BJP and the Left," Ramesh said.
He said, while the Bharatiya Janata Party-led National Democratic Alliance (NDA) government in 1998-2004 issued 32 coal blocks, it was the UPA government which issued public advertisements to invite applications for allocation of coal blocks in 2005 and went ahead with the screening process in a "very transparent manner".
Ramesh said the government "was not sleeping on the issue" and had started the process of scrutinising the performance of coal companies in January itself but the inter-ministerial group, looking into the issue, was formed in May, 2012.
"The IMG report is very crucial...it will come in a few days and establish why coal was not produced in some mines," said Ramesh.
The minister circulated a list of eight "inconvenient truths" for the BJP and said that in mid 2005 some party chief ministers-Vasundhara Raje of Rajasthan and Raman Singh of Chhattisgarh including BJD Chief Minister Naveen Patnaik in Odisha had objected in writing against introduction of the competitive bidding.
He said Singh and Patnaik had even written letters recommending coal blocks to companies now being termed "tainted".
Comptroller and Auditor General's (CAG) report on coal blocks allocations has suggested a presumptive loss of Rs.1.86 lakh crore ($37 billion).
He said former BJP minister Arun Shourie had termed the CAG report on "Coffingate" in 2001 as "idiotic".