"Our PM can never do anything wrong. And if anyone levels such allegations that the PM has done something wrong, then there is no correctness (or) facts to that allegation," Sibal told reporters here.
The Comptroller and Auditor General (CAG) in its report last week stated that coal blocks allocated since 2004 to private firms for captive usage without bidding amounted to extending undue financial bid of about Rs 1.86 lakh crore. Singh held the coal portfolio for most of the duration.
"We know our PM and we know that someone else can do something wrong but the PM cannot," Sibal said.
He said coal-bearing states of Chattisgarh, West Bengal, Odisha, Jharkhand and Madhya Pradesh, where the Congress was not in power, had opposed allocation of coal mines to private firms through competitive bidding or auction.
"Chattisgarh, West Bengal, Odisha, Jharkhand and Madhya Pradesh, we are not the governments in these states. All chief ministers were in agreement and said coal blocks should not be auctioned. This should be investigated, what did they say (on auction of coal block? (Only) then allegations should be made," he said.
He demanded that there should be debate on the issue and that "there should be a politics of debate and not that of allegations and counter-allegations".
"There should be investigation into the allegations, what were the policies since the 1990s, what happened earlier, how coal blocks were allocated after 1993, that needs to be investigated. Who brought in transparency that should be investigated. It was our PM who first talked of bringing in transparency," Sibal added.